RB1100AHx2 slowed to a crawl

StattorZ · February 17, 2016, 10:24pm

I’ve run in to an interesting problem. Client mentioned network speeds have slowed to a crawl and upon further investigation I’ve narrowed it down to the RB1100AHx2. But I can’t figure out what the issue is. Pings are exceeding 400ms at router level with no other devices connected. Already tested at modem. Reboot through win box restores speed briefly, but soon slows back down. Even without any other devices, WAN port is still sending 13+Mbps on the TX.

This configuration has been solid for about a year. Troubleshooting ideas?

jarda · February 17, 2016, 10:44pm

Probably like always here. You are part of attack via abusing your dns service opened to Internet. I guess. Be sure there is not allowed any unwanted traffic in input chain. Especially the dst port 53 is dropped on your wan interface in input chain.

StattorZ · February 17, 2016, 11:00pm

Would you mind clarifying the rule needed?

BartoszP · February 18, 2016, 9:22am

add action=drop chain=input comment="DNS via UDP" dst-address-list=MYPRECIOUSWANIPS dst-port=53 protocol=udp

or

add action=drop chain=input comment="DNS via UDP" in-interface=MY-WAN-INTERFACE dst-port=53 protocol=udp

inteq · February 20, 2016, 6:16am

Enable connection tracking and see what is doing what?

p3rad0x · February 22, 2016, 12:06pm

Also,

Can you see any strange traffic on the interfaces?

Also check at what speeds all the ethernet ports are running at.

You should also check cpu usage.