I have a RouterOS hotspot (level 6) running at my core location. Behind it I have a few servers and a couple of other Mtik hotspots. My problem is:
After a period of time (hours) everything behind the core hotspot can't ping the DNS servers. The core hotspot router can ping the DNS servers but nothing behind it can. As soon as I turn off the hotspot server on the core router I can ping the DNS servers. When I turn the hotspot back on after some time I lose DNS connectivity again.
What I have done to troubleshoot:
Tried pinging other IPs outside the network: works, just DNS IPs don't respond
Cleared DNS cache on the core hotspot router: still couldn't ping DNS IPs
Turned off connection tracking on the core hotspot router: still couldn't ping DNS
Turned off hotpot on the core router: I could ping DNS servers
Turned hotspot back on: I could still ping the DNS servers but after a few hours I lose connectivity to DNS
I am not sure what exactly happens over a period of time. Something fills up or the hotspot proxy crashes? It's not connection tracking since turning that feature off didn't make a difference. The CPU load and memory usage were also fine on the core hotspot server when this happened. How do I turn off DNS caching (I am not sure if this could be the issue either)?
I am running version 4.11 on an x86 box. I have the number of hotspot users set to 3000 but don't come anywhere near this number (only have a 100 or so users). All idle timeouts, etc have been turned off. If I leave the hotspot service off everything is fine. I have the hotspot running on its own vlan interface. Initially it was running on the same vlan as everything else (servers, other hotspots, etc) and this problem would occur withing 5~10 mins. Now it takes hours but still happens.