First off I use Mikrotik extensively for my WISP as our edge, core, and tower routers and never have had any issues. Any way I have just installed at my home a 750GL in a standard soho setup and I am having a hard to track down issue that may be router related?

Background:
I just got setup with a local FTTH provider and switched from my previous provider. They provide me a 100/25meg service. My old router I have had for over 5 years (no issues) WRT54GL running Tomato (openwrt variant) had to be replaced as it cannot push more than 50mbps.

Issue:
I upgraded to 6.32.3 on the 750 and modified the default config slightly. I changed the private LAN IP and the DHCP subnet and pool size. I setup some static DHCP leases, changed the password, locked down the IP->Services to local subnet only, and I setup a basic firewall. I kept the default NAT rule and am not doing port forwarding.

Anyway it seemed to work great the first evening, but the next day my wife said the internet was flaky during the day. Constant pages not loading for a while and then loading fine later. I got home that evening at everything seemed fine. The next day the same thing. Now I am thinking it is an ISP issue so I go home and try to reproduce the issue before I call their support line.

I got home an was able to reproduce the issue on my wired PC and my work laptop when connected to the router. Pages would randomly not load and then a few minutes later everything would be fine for a while and then not load again. Not always the same pages and not every website. For example Microsoft would not load but yahoo was still working fine. Later Yahoo would not load and Microsoft would be ok.

During these drop outs ICMP is running fine and I showed no packed loss or high latency to yahoo or google. DNS resolution was working along with traceroutes. Connections that were already running like an RDP session or DUDE connection once loaded would not drop, but if I disconnect sometimes I could not reconnect.

As you can imagine I was quite perplexed. During a time when the drops were quite bad I bypassed the router and could not reproduce the issue on my laptop. Plugged back into the router and the issue would start up again.

I connected to the old wrt54gl router and cannot reproduce the issue. Of course my ISP said it must be your router.

One thing that muddies the waters some is how this ISP hands out addresses. My router gets DHCP from a /19 private subnet which is then NAT'd on their end to a public IP. Each device that I plug into their handoff ends up with a different public IP so it is hard to know if it is an IP issue on their end or not.

Because of that I decided to look deeper at the public IPs I was getting. My pc and my old router would get 208.38.x.x addresses, but my 750 would get 192.69.x.x address. It got me wondering if the 192.69 subnet was the problem.

I then reconfigured the WAN port on the 750 to a different port until I was able to end up in the 208.38 subnet. Everything seemed fine, but last night the drop outs happened again on the 750. I have since switched back to the wrt54gl router and cannot reproduce the issue.

Things I have tried on the 750gl.
1. Upgrade from 6.32.3 to 6.33 - did not help
2. Turn off all firewall rules and only have the one masq nat rule - no help
3. Downgrade to 5.26 - did not help

Does anyone have any suggestions or advice? At this point I will run the wrt54gl for a few days and if no issue I will put back the 750 and see if it starts up again. If it does I may have to buy a router other than MK for my home.

So far since defaulting the 750, removing the default config, and reprogramming from scratch I have not had any further issues.

I tested sending 1500 byte packets with Dont Fragment set and they go through fine. Anything larger than 1500 comes back as too large. That is what I would expect as my MTU is set to 1500.

Appears to have been an issue with taking the default config on a 750 (was running 5.16 originally) and then upgrading to 6.32.3 while keeping that config.

Also, I might add that I created this thread on the MK forum and the UBNT forum the same day.

MK forum - 73 views no posts or help
UBNT forum - 176 views 35 posts

Kind of disappointing that I get more help on UBNT forum for MK equipment than on MK official forum.

Kind of disappointing that I get more help on UBNT forum for MK equipment than on MK official forum.

Many readers will skip a longwinded post like yours, TLDR.

Kind of disappointing that I get more help on UBNT forum for MK equipment than on MK official forum.

Many readers will skip a longwinded post like yours, TLDR.

Wow!!

I had a similar issue when I left dns wide open on the router. There were always bots trying to ddos it.

I had a similar situation like yours with 75x and 95x routers.

I dont know why, sometimes the link between two equipment (hardware link) start to changing and faultily.

The last time was about two months ago between a Hudge 9650 Vsat modem and the 951 G router. The link must be at 100 Mbps but the router changes continuously between 100 and 1 Gbps (the Hudge is 100 Mbps) but the MK try every moment to change to 1 Gbps. After minutes the connection fails and fails more.

Solution, setup the connection in the Ethernet just to 100 Mbps full and half duplex.

I discovered it in the modem Hudge logs.

Try to setup the Ether WAN to a fixed speed.