LtAP LTE6 regularly disconnects from LTE network

gabacho4 · Thu Dec 31, 2020 8:13 am

Hello all,

I am a new mikrotik user and have been using a LtAP LTE6 to connect to an LTE network for internet access in my home network. I am on ROS 6.46.8 and the modem is on firmware V26. When I first purchased the devise the network connection was incredibly stable and fast. Since updating the modem, or possibly the ROS version, I now suffer from disconnects that take my network down for a little over a minute. I tried ROS 6.48 to see if that would have any positive effect on my situation but it did not. I've also completely reset the router and that has made no difference. I have a very simple setup with the LtAP only connecting to the LTE network and then serving as the uplink for a pfsense router. I've seen other postings on this forum that suggest there is a problem with the modem firmware.

I have enabled logging and do notice what I believe is the problem that is occurring. Here is the output of the latest event at 0618 this morning. I see the same type of issues every time the network connection dies. Would appreciate any help or confirmation of a firmware bug that anyone can provide.

06:18:52 lte,async,raw lte1: +CREG: 0 
06:18:52 lte,async,raw lte1: $CREG: 0 
06:18:52 lte,async,event lte1: ^MODE:3 
06:18:52 lte,async,event lte1: +MSRI: 1 
06:18:53 lte,async,event lte1: +MPBK: 0 
06:18:53 lte,async,event lte1: *SIMDETEC:2,NOS 
06:18:53 lte,async,event lte1: +MMSG: 0, 0 
06:18:53 lte,async,raw lte1: +CGREG: 0 
06:18:53 lte,async,raw lte1: +CEREG: 0 
06:18:53 lte,info lte1: not registred, state: 0 
06:18:53 lte,async,event lte1: +CPAS: 5 
06:18:53 lte,async,event lte1: *SIMDETEC:1,SIM 
06:18:54 lte,async,raw lte1: sent AT+CFUN? 
06:18:54 lte,async,raw lte1: rcvd +CFUN: 4 
06:18:54 lte,async,event lte1: *ICCID: 6768008 
06:18:54 lte,async,event lte1: *EUICC: 1 
06:18:54 lte,async,raw lte1: +CREG: 0 
06:18:54 lte,async,raw lte1: $CREG: 0 
06:18:54 lte,async,raw lte1: +CGREG: 0 
06:18:54 lte,async,raw lte1: +CEREG: 0 
06:18:54 lte,async,event lte1: *RADIOPOWER: 0 
06:18:55 lte,async,event lte1: *ADMINDATA: 0, 0, 0 
06:18:55 lte,async,event lte1: +CPIN: READY 
06:18:55 lte,async,event lte1: *EUICC: 1 
06:18:55 lte,async,event lte1: *ECCLIST: 5, 0, 112, 0, 000, 0, 08, 0, 118, 0, 911 
06:18:55 lte,async,event lte1: +MMSG: 0, 0 
06:18:58 lte,async,event lte1: +MMSG: 0, 1 
06:18:58 lte,async,event lte1: +MPBK: 1 
06:19:01 lte,async,event lte1: +MMSG: 1, 1 
06:19:53 lte,error failed to register on network 
06:19:53 lte,account lte1 session: 30947s 7495017348/396975471 bytes 5695852/2162343 packets 
06:19:53 lte,async lte1: sent AT+CFUN=4 
06:19:53 interface,info lte1 link down 
06:19:53 lte,async lte1: rcvd OK 
06:19:53 lte,async lte1: sent AT+EEMOPT=1 
06:19:53 lte,async,event lte1: *RADIOPOWER: 0 
06:19:53 lte,async lte1: rcvd OK 
06:19:53 lte,async lte1: sent AT*MRD_SN? 
06:19:53 lte,async lte1: rcvd *MRD_SN:30DB6B7 
06:19:53 lte,async lte1: sent AT+CPIN? 
06:19:53 lte,async lte1: rcvd +CPIN: READY 
06:19:54 lte,async,raw lte1: sent AT+CFUN? 
06:19:54 lte,async,raw lte1: rcvd +CFUN: 4 
06:19:57 lte,async lte1: sent AT+CPMS="SM","SM","SM" 
06:19:57 lte,async,event lte1: +MMSG: 1, 1 
06:19:57 lte,async lte1: rcvd +CPMS: 60,60,60,60,60,60 
06:19:57 lte,async lte1: sent AT+CFUN? 
06:19:57 lte,async lte1: rcvd +CFUN: 4 
06:19:57 lte,async lte1: sent AT*ICCID? 
06:19:57 lte,async lte1: rcvd *ICCID: 68008 
06:19:57 lte,async lte1: sent AT+CNUM 
06:19:57 lte,async lte1: rcvd  
06:19:57 lte,async lte1: sent AT+CIMI 
06:19:57 lte,async lte1: rcvd 7861563 
06:19:57 lte,async lte1: sent AT+CPIN? 
06:19:57 lte,async lte1: rcvd +CPIN: READY 
06:19:57 lte,async lte1: sent AT*BAND? 
06:19:57 lte,async lte1: rcvd *BAND: 5, 78, 147, 0, 524289, 0, 2, 2, 0 
06:19:57 lte,async lte1: sent AT*BAND=5,78,147,0,524289,0,2,0 
06:19:57 lte,async lte1: rcvd OK 
06:19:57 lte,async lte1: sent AT*lteband=3,7,1,20,12,17,2,25,26,5,8,38,41,40,39 
06:19:57 lte,async lte1: rcvd OK 
06:19:58 lte,async lte1: sent AT+ZGDCONT=5,"IP","apn1",0 
06:19:58 lte,async lte1: rcvd OK 
06:19:58 lte,async lte1: sent AT+ZGPCOAUTH=5,"","",0 
06:19:58 lte,async lte1: rcvd OK 
06:19:58 lte,async lte1: sent AT+COPS=0 
06:19:58 lte,async lte1: rcvd OK 
06:19:58 lte,async lte1: sent AT+COPS=3,0 
06:19:58 lte,async lte1: rcvd OK 
06:19:58 lte,async lte1: sent AT+CFUN=1 
06:19:58 lte,async,event lte1: +CPAS: 2 
06:19:58 lte,async,event lte1: *RADIOPOWER: 1 
06:19:58 lte,async lte1: rcvd OK 
06:19:58 lte,debug lte1: config ok 
06:19:59 lte,async,raw lte1: +CEREG: 1,"a065","00060a05",7 
06:19:59 lte,debug lte1: network access technology: Evolved 3G (LTE) 
06:19:59 lte,info lte1: registered home 
06:19:59 lte,async,raw lte1: +CGREG: 0 
06:19:59 lte,async,event lte1: +CIREPI: 1 
06:19:59 lte,async,event lte1: +CPAS: 0 
06:19:59 lte,async,raw lte1: +CREG: 6,"a065","00060a05",7 
06:19:59 lte,async,raw lte1: $CREG: 6,"a065","00060a05",7,"170" 
06:19:59 lte,async,event lte1: +CEN1: 1, 419, 02 
06:19:59 lte,async,event lte1: +CGEV: EPS PDN ACT 5 
06:19:59 lte,async,event lte1: *COPN:0,Zain KW 
06:19:59 lte,async,event lte1: *COPN:1,Zain KW 
06:20:00 lte,async,event lte1: +ZNITZ: 2020,12,30,30,19,58,32,0 
06:20:00 lte,async,event lte1: +NITZ: 0,+12,20/12/31,03:19:58 
06:20:00 lte,async,raw lte1: +CREG: 6,"a065","00060a05",9 
06:20:00 lte,async,raw lte1: $CREG: 6,"a065","00060a05",9,"170" 
06:20:00 lte,async,raw lte1: +CEREG: 1,"a065","00060a05",9 
06:20:01 lte,async,raw lte1: sent AT+CFUN? 
06:20:01 lte,async,raw lte1: rcvd +CFUN: 1 
06:20:01 lte,async,raw lte1: sent AT+COPS? 
06:20:01 lte,async,raw lte1: rcvd +COPS: 0,0,"Zain KW",9 
06:20:04 lte,async lte1: sent AT+ZGACT=1,5 
06:20:04 lte,async lte1: rcvd OK 
06:20:07 lte,async,event lte1: +ZCONSTAT: 1,5 
06:20:07 lte,async,event lte1: +ZGIPDNS: 5,"IP","37.34.183.193","37.34.183.193","212.43.17.11","95.66.17.12","","","","" 
06:20:07 interface,info lte1 link up

gabacho4 · Sat Jan 02, 2021 7:45 am

Any ideas at all? This issue is happening far too frequently and I've done everything I can to try to address it. I've reset the router, wiped the configuration and used the default, and run commands to reset the modem. Nothing works. In the meantime, I've had many more outages. I really like(d) my LtAP LTE6 but I'm getting to the point I'm going to have to replace it with my ASUS 4G-AC68U. Would be a shame as I was hoping to learn up on Mikrotik.

killersoft · Sun Jan 03, 2021 5:58 am

Hi, have you installed the external antenna's for the unit, also what is your signal strength indicators RSRP/RSRQ/SINR etc ?
Also what if your providers frequency's/band's V.S what LTE/4G towers(and there associated frequencies/band) are nearby.
https://www.youtube.com/watch?v=ysiSoglchg0
I installed external antenna's on my ltAP because the internal antenna's are not good when your say ~4Km+ away from a tower, external is cheap and the antenna's you get can be more specific to the frequeny band your targeting using for your provider.

Did you update the LTE card's firmware version(usually via over the air update) OR just RouterOS + The ltAP(board-firmware too) ?
Board firmware ->https://wiki.mikrotik.com/wiki/File:Rb_upgrade4.jpg
LTE Card Firmware- >https://wiki.mikrotik.com/wiki/Manual:I ... re_upgrade
Assuming you have a mikrotik LTE card in it. I swapped it eventually to a 3rd party card for more frequencies/bands.

gabacho4 · Sun Jan 03, 2021 8:54 am

@killersoft - I have installed external antennas using all Mikrotik hardware ( 2 x MikroTik ACSMAUFL U.fl-SMA Female Pigtail for wAP R and 1 x MikroTik MTAO-LTE-5D-SQ 699-2690MHz Omni Antenna LTE).

I am literally right across the street from the provider's tower and have the following signal strength levels (RSRP: -51 dBM, RSRQ: -6.5 dB, SINR: 27.0dB). Pretty much the best signal I think you can get minus owning the tower itself.

LtAP is always connecting to Band1 and Band20. The scans that I have done show Bands 1, 3, 7, 8, 20 active around me though B1 and B20 are the most frequently appearing. Modem is able to use any of those bands. B1 and B20 are the best quality ones. I have only LTE selected as the network mode as 3G does not give great speeds.

I have updated the routerboard firmware (it's 6.46.8) as well as the router OS via the command line (I'm using the latest LTS version), and have done the same with the LTE modem as well (now on R11e-LTE6_V026). I had 0 problems with the connection for some time but believe modem firmware V25 or V26 has an issue. I find postings about issues similar to mine on the forum and @SiB seems to indicate that there is a V26 issue and V27 had addressed it. However details are very scant and V27 isn't available yet. I was hoping someone smarter than me could look at the log and confirm if it's the same issue or if I'm dealing with something else. I've also reached out to Mikrotik support but haven't heard back.

Appreciate your time and thoughts.

killersoft · Sun Jan 03, 2021 1:35 pm

Hi,
Yes, you should not have issues with that antenna, or those signal levels.( maybe you have too much signal LOL(wrap some aluminum around the external antennas to drop it back ! )
I note your probably doing Carrier Aggregation on B1 + B20. I wonder if you force the modem to only do band 1 OR 20, but not both, how that would go ?.
Could be a provider / tower issue ?, although you would think that would be unlikely, given its mature tech nowadays.
How are you powering the Ltap ?, does it have a beefy enough(amperage) power supply ?.
Also do you have basic firewall/NAT rules etc, and not loading down the unit with endless firewall rules etc(CPU intensive) ?

gabacho4 · Sun Jan 03, 2021 3:03 pm

@killersoft - is it possible to have too strong a signal? Seriously. Could that cause some sort of weird overdrive issue or something similar? I can easily break out the tin foil or reattach the stock antennas if so.

I am using the power supply provided with the device. Shouldn't be an issue there. No issues with undervoltage or hard shutdowns.

I've tried the sim in my ASUS 4G router and had NO issues over the course of 48 hours. No indications this a provider issue though I did contact the provider initially to see if there were network issues or any problems with my account and was told there was nothing. Again the experience with my ASUS router strongly suggests that this is a Mikrotik issue.

I have essentially a default configuration in place minus turning off web access and creating a non admin user account etc. I have 3 port forwarding (dsnat) rules in place for access to my pfsense router via ssh and openvpn.

As I mentioned, things were running beautifully for quite some time. I'm am more and more convinced that there is a modem firmware issue based on what I've read. Why the modem believes there is no SIM at one point, only to recognize the same SIM that was always there, makes no sense to me. I'm running on 6 hours connection time with no issues so we'll see how much longer it lasts. I am regularly checking to see if there is a new modem firmware available. Mikrotik probably thinks they are getting DDOS'ed. 😀

killersoft · Mon Jan 04, 2021 12:49 am

Well, yes, you can overdrive a RF front end pretty easily. I'm a ham radio operator too, and have experienced that for myself on RF equipment.
You can also simulate that with an Access point and a client sitting on top of one-another, notable throughput can drop a bit, as opposed to being ~1meter away, I'm guessing you can do that with 4G/LTE too, but I have no plans on sitting that close to a provider tower at frequencies > 1GHz, with EIRP's > 25Watts in front of a gain'ed antenna!! to test that theory...

I wonder if you go back to an older RoS build or more specifically a LONG-TERM build if you see the same issue, would be interesting to see if its the minipcie card or RoS causing it thou.

gabacho4 · Tue Jan 05, 2021 11:26 pm

Just to help anyone else that might encounter a similar issue, the help Mikrotik provided me was:

1. I have one of those SIM cards thst allows you to pop the varying SIM sizes out of to use in your phone or modem. Mikrotik told me they can be thinner than a solid full-size SIM card. I was advised to put a few layers of scotch tape on the back of the SIM to make it fit tighter in the SIM slot. Easily done. SIM is definitely more snug.

2. I was provided a link to download what I have to assume is a beta, or as yet unreleased, LTE6 modem firmware V27 and instructions to upload the file to my router, disable the LTE interface, and then run a specific command for the new firmware to be installed on the modem. I initially had errors when trying to install and it turns out that my copy of V27 cannot be installed on latest LTS version but has to be installed on latest stable. No big deal. I updated to 6.48 stable and was successfully able to update the modem to V27.

At this time, I'm going on 10 hours runtime with no interruption of my internet service. This is one of the longest periods of uninterrupted connectivity I have enjoyed in the past week or so. So, pending a few more days of monitoring, it appears that either the taped SIM card, or modem firmware V27, or both, have fixed my issue. Will advise in a few days with final results.

killersoft · Wed Jan 06, 2021 12:45 am

I did not think about the SIM card, as an issue, but yes that could cause random issues. That said, if it was working well before you upgraded, it might not be sim card issue.

islamlaipanov · Wed Jan 06, 2021 2:25 pm

Just to help anyone else that might encounter a similar issue, the help Mikrotik provided me was:

1. I have one of those SIM cards thst allows you to pop the varying SIM sizes out of to use in your phone or modem. Mikrotik told me they can be thinner than a solid full-size SIM card. I was advised to put a few layers of scotch tape on the back of the SIM to make it fit tighter in the SIM slot. Easily done. SIM is definitely more snug.

2. I was provided a link to download what I have to assume is a beta, or as yet unreleased, LTE6 modem firmware V27 and instructions to upload the file to my router, disable the LTE interface, and then run a specific command for the new firmware to be installed on the modem. I initially had errors when trying to install and it turns out that my copy of V27 cannot be installed on latest LTS version but has to be installed on latest stable. No big deal. I updated to 6.48 stable and was successfully able to update the modem to V27.

At this time, I'm going on 10 hours runtime with no interruption of my internet service. This is one of the longest periods of uninterrupted connectivity I have enjoyed in the past week or so. So, pending a few more days of monitoring, it appears that either the taped SIM card, or modem firmware V27, or both, have fixed my issue. Will advise in a few days with final results.

Hi gabacho4! What's up with your issue? Have you fixed it? I have this issue too with lhg lte6 kit. My connection fails every 30-40 minutes with "failed to register on network" error.
I have updated my lte, routerboard firmware and ros, but I still have the problem. Can you help me and tell how you fixed the issue, please?

gabacho4 · Wed Jan 06, 2021 5:14 pm

Unfortunately the problem isn't resolved still. I've had two disconnects since I posted last. The issue appears to be different but I suspect it's still related. My LtAP says it's connected and but I cannot ping anything like 8.8.8.8 and dns resolution does not work. I have to disable the LTE interface and re-enable it and then things work fine. Working with Mikrotik for next steps to troubleshoot.

islamlaipanov · Wed Jan 06, 2021 6:49 pm

Unfortunately the problem isn't resolved still. I've had two disconnects since I posted last. The issue appears to be different but I suspect it's still related. My LtAP says it's connected and but I cannot ping anything like 8.8.8.8 and dns resolution does not work. I have to disable the LTE interface and re-enable it and then things work fine. Working with Mikrotik for next steps to troubleshoot.

I had problems with dns too. I've solved it by turning off "Use peer DNS" in LTE APN and by setting google's dns adresses: "8.8.8.8" and "8.8.4.4" in DNS Settings. The problem with dns resolving appeared on mobile devices, by the way.

I made ips sim card thicker, but it didn't help me.

LtAP LTE6 regularly disconnects from LTE network

LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

Re: LtAP LTE6 regularly disconnects from LTE network

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