RB751U-2HnD crashing when using Skype

RouterOS Beginner Basics
1

I am using a RB751U-2HnD and have a problem where the router regularly restarts when using Skype from a machine on the LAN. I usually use Skype on a wireless connection from a Macbook. This is very frustrating but I must be doing something wrong as I cannot believe Mikrotik would fail at Skype! What happens is Skype call drops, no access to the web, then network comes back up (or I plug ethernet in) and when I login to Winbox the uptime corresponds to the recent crash.

I am running RouterOS 5.11 and believe I have enabled uPNP. Below shows the usual outputs, if any more would be helpful please let me know. It may be something to do with MTU or MSS (there are mangle rules to alter MSS than don’t seem to print from command line?

I don’t fully understand how to setup logging so the MT won’t loose records when restarting.

Any advice very much appreciated.

Crude Network Diagram
ADSL --[telephone]-- MODEM ----[cat5]----Mikrotik-----LAN (+ Wifi)

/ip address print detail
Flags: X - disabled, I - invalid, D - dynamic
0 ;;; local LAN
address=192.168.88.1/24 network=192.168.88.0 interface=bridge-local
actual-interface=bridge-local

1 D address=192.168.1.10/24 network=192.168.1.0 interface=ether1-gateway
actual-interface=ether1-gateway

2 D address=111.xxx.xxx.xxx/32 network=111.xxx.xxx.xxx interface=pppoe-out1
actual-interface=pppoe-out1



/ip route print detail
Flags: X - disabled, A - active, D - dynamic,
C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme,
B - blackhole, U - unreachable, P - prohibit
0 ADS dst-address=0.0.0.0/0 gateway=111..xxx.xxx.xxx
gateway-status=111.xxx.xxx.xxx reachable pppoe-out1 distance=1 scope=30
target-scope=10

1 ADC dst-address=111..xxx.xxx.xxx/32 pref-src=111.69.245.4 gateway=pppoe-out1
gateway-status=pppoe-out1 reachable distance=0 scope=10

2 ADC dst-address=192.168.1.0/24 pref-src=192.168.1.10 gateway=ether1-gateway
gateway-status=ether1-gateway reachable distance=0 scope=10

3 ADC dst-address=192.168.88.0/24 pref-src=192.168.88.1 gateway=bridge-local
gateway-status=bridge-local reachable distance=0 scope=10



/interface print detail
Flags: D - dynamic, X - disabled, R - running, S - slave
0 R name=“wlan1” type=“wlan” mtu=1500 l2mtu=2290

1 R name=“ether1-gateway” type=“ether” mtu=1500 l2mtu=1600 max-l2mtu=4076

2 R name=“ether2-master-local” type=“ether” mtu=1500 l2mtu=1598 max-l2mtu=2028

3 R name=“ether3-slave-local” type=“ether” mtu=1500 l2mtu=1598 max-l2mtu=2028

4 name=“ether4-slave-local” type=“ether” mtu=1500 l2mtu=1598 max-l2mtu=2028

5 name=“ether5-alone” type=“ether” mtu=1500 l2mtu=1598 max-l2mtu=2028

6 R name=“bridge-local” type=“bridge” mtu=1500 l2mtu=1598

7 R name=“pppoe-out1” type=“pppoe-out” mtu=1492



/ip firewall export

jan/15/2012 17:51:02 by RouterOS 5.11

software id = XXXX-XXXX

/ip firewall connection tracking
set enabled=yes generic-timeout=10m icmp-timeout=10s tcp-close-timeout=10s
tcp-close-wait-timeout=10s tcp-established-timeout=1d tcp-fin-wait-timeout=
10s tcp-last-ack-timeout=10s tcp-syn-received-timeout=5s
tcp-syn-sent-timeout=5s tcp-syncookie=no tcp-time-wait-timeout=10s
udp-stream-timeout=3m udp-timeout=10s
/ip firewall filter
add action=accept chain=forward disabled=no dst-address=192.168.1.1
in-interface=bridge-local out-interface=ether1-gateway
add action=accept chain=output comment=PPTP_GRE disabled=no protocol=gre
add action=accept chain=input comment=PPTP_GRE disabled=no protocol=gre
add action=accept chain=input comment=“default configuration - PPTP” disabled=
no dst-port=1723 in-interface=pppoe-out1 protocol=tcp
add action=accept chain=input comment=“default configuration” disabled=no
protocol=icmp
add action=accept chain=input comment=“default configuration” connection-state=
established disabled=no
add action=accept chain=input comment=
“This is to enable ODMON SNMP checking remotely.” disabled=no dst-port=161
protocol=udp src-address=188.124.160.10
add action=accept chain=input comment=“default configuration” connection-state=
related disabled=no
add action=drop chain=input comment=“default configuration” disabled=no
in-interface=pppoe-out1
/ip firewall mangle
add action=mark-packet chain=forward comment=VoIP disabled=no new-packet-mark=
VoIP passthrough=no src-address=192.168.88.200
add action=mark-packet chain=forward comment=VoIP disabled=no dst-address=
192.168.88.200 new-packet-mark=VoIP passthrough=no
/ip firewall nat
add action=redirect chain=dstnat comment=“For proxy” disabled=yes dst-port=80
protocol=tcp to-ports=8080
add action=masquerade chain=srcnat comment=“default configuration” disabled=no
out-interface=pppoe-out1
add action=masquerade chain=srcnat comment=
“This is required to access Vigor modem on 192.168.1.1” disabled=no
out-interface=ether1-gateway
/ip firewall service-port
set ftp disabled=no ports=21
set tftp disabled=no ports=69
set irc disabled=no ports=6667
set h323 disabled=no
set sip disabled=yes ports=5060,5061,50600 sip-direct-media=yes
set pptp disabled=no



/ip upnp print
enabled: yes
allow-disable-external-interface: yes
show-dummy-rule: yes

2

I had the same issue when pushing any amount of data over the 751. What I had done is left the same power supply in place that came with the 750 which is 12V - 500mA and the board was not getting enough power. The 751 comes with a 12V -1A but I did not have one and used a 24V instead. I am not sure if it is recommended to use a 24V with the 751 but it has been working for me. Maybe someone else could elaborate on that.

3

cbrown - thanks for the idea.

I was using the 24v 0.8amp that was supplied. I will try with a 12v 1.25amp I have and see if that improves things. I bought from a reputable reseller so would hope they were supplying decent power supplies.

If anyone else has other ideas please add them.

4

you have only one device that is experiencing such problems?
What routerboard firmware you are using now?
Can you tell us the best way how to reproduce this reboot using the skype - what should be do (step by step)?

5

This is my one and only Mikrotik device - the first one I have ever used. I am trialling in at home in preparation for a deployment of 16+ and a 450G for work - but if I can’t sort this than that deployment won’t happen :frowning:

I am using RouterOS 5.11, but have upgrade from 5.9 and 5.10 - all experience the same problem.

The best way to reproduce it is to use Skype - voice or video call. I am usually calling from Australasia to Europe. I’m using a Macbook (Skype version 5.3), and travel with it - so sometime Skype would be open and logged in when I connect, and sometime Skype would startup when already connected. I note this as it may have something to do with uPNP access? It appears at random times but has been happening over a period of weeks, and ever since I had the device. It works with another Mac as well. I don’t have a Windows box to test.

I am wondering if I can put any logging (that will save to USB or survive a reboot) or watch anything whilst on a call (e.g. NAT tables etc?). The CPU seems to rise, but not be pegged at 100%.

Any ideas?

6

What do you see in the ‘system routerboard’ section - what bios version? Have you tried to disable the uPNP, does it still crash?

7

Current firmware is 2.36, and upgrade firmware is 2.37 - the change log only indicates a couple of unrelated things. Do you recommend I upgrade?

Potentially useful - in System > Health, I get an empty box.

uPNP was disabled by default, and I had the problem. I enabled it after reading that Skype would need it otherwise it could/would fill the memory up due to a large number of connections.

8

I have not been using this device much, but can confirm the issue still happens with the different 12v 1.25a PSU, so I do not think PSU draw is the issue. It doesn’t hang doing anything else - including extensive down/up loading, considerably more machines etc. But just Skype on a single machine forces a crash :frowning:

My next steps are to upgrade the firmware, try without uPNP, and then I will wipe the config and start from scratch, building up a basic setup and making sure I understand how everything works.

I am still very much open to advice and suggestions :slight_smile:

9

upgrade to RoutrerOS v5.12 and upgrade the bios to v2.38
Do you have some eoip or pptp tunnels?

10

I have now upgraded.

One PPTP VPN access for when I am offsite - rarely used.

11

I upgrade to latest firmware and routeros as above.
I’ve upgraded to a 12v 2A PSU incase it was this.
I have simplified my setup - a PPPoE WAN connection, DHCP server for ethernet and Wifi, SNMP for monitoring.
I still have random reboots. When it comes back up my log file says:

jan/02/1970 12:00:17 system,error,critical router was rebooted without proper shutdown (cause 1)

This is getting to the point where the device is unusable and I do not know what else I can try to sort. It I have tried two different WAN connections in two different locations, and have the same issues. Consumer (D-Link and Netgear) have no problems in either location.
Any other ideas?

12

I wish I knew what to tell you. Have you tried a 24V 1a PSU? Since I put that on my 751 the reboot issue disappeared. But I am also no electrical engineer. :slight_smile:

13

This is a diffrent issue, not related to this topic. Changing the PSU adapter is only a temporary fix, you need to repair the device, contact seller for RMA repair.

14

I also have router reboots while using Skype.

[@MikroTik] /system routerboard> p
       routerboard: yes
             model: 751U-2HnD
     serial-number: 2C4F0139F0A1
  current-firmware: 2.37
  upgrade-firmware: 2.37

I’ve tried to investigate this issues, it looks like flash process consumes a lot of CPU (80-100%). Router almost do not respond on other requests (ssh login, web login and so on) so it is hard to watch this situation in live.

What kind of information could be useful for debugging this issue? It is very annoying =(

15

lostar, sorry to hear you are having the same problem. I am being told to change the power adaptor - but I have tried three and it has not fixed the issue. What PSU are you using? Do you use wireless devices, and if so what? I use macbooks, iPad, iPhone and Android devices. I’m wondering if there is a compatibility issue…

16

I’m using PSU 12V, 1A (bundled with RB751U).
In my network a lot of apple devices (MacBookAir, MacBook Pro, iPhone, iPad) and some Android based devices. Last time Skype was running on MacBook Air - wireless connection was used.
Router establish l2tp connection with my ISP for internet access.

17

Interesting - I have a similar setup, and a Macbook Air has problems (along with the Macbook, and a couple of Android devices will be connected at the same time). The ‘flash’ process jumps up to high CPU usage when I use Skype - and this process is “cpu usage when writing to NAND” according to http://wiki.mikrotik.com/wiki/Manual:Tools/Profiler. I’m not sure why Skype would cause the device to write to NAND? Does anybody have more ideas apart from a PSU? I have had the same problem using the (same) device with another config and a different type of WAN connection…

I am willing to explore other options e.g. wifi config errors etc - but the problem manifests itself when using Skype - everything else is stable. Very frustrating!

18

I just did some more testing:

  • Running Winbox on Macbook connected to Wifi
  • Skype video conversation on Macbook Air connected to Wifi
  • Winbox profiler shows ‘flash’ process jumping to ~80% (CPU at 100%)
  • Winbox disconnects
  • Macbook and Android phone are not able to browse the web / Winbox will not connect / Webfig will not load
  • In this instance Skype call did not drop, but all other connectivity did.
  • When Skype call finished, other devices could browse the web again.

At start of Skype call, sectors written since reboot was 2,536. After 30 minutes of Skype call, this was 4,112. Does this sound correct?

19

+1 Same here Skype on wireless with ROS 5.12 and FW 2.38. There is no tunnels configured.

20

I have narrowed this down to the wireless interface and posted my findings here: http://forum.mikrotik.com/t/rb751u-2hnd-issues-with-wireless-skype-100-cpu-flash/54008/2
I have tried both 12v and 24v PSU so I don’t believe that is the issue.