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New Member

1811 router - high cpu load in dual wan config

Hi there,

I have a problem with an 1811w router that has so far eluded all my atempts at solving it.

The setup is fairly simple: I have 2 unequal ISP connections that service several computers acrosss a lan, based on access lists (some go through ISP1, some go through ISP2). In the event of a loss of conectivity on either line, the other one should take over gracefully.

I've managed to get the router setup properly and everything works as it should... for a while.

For some reason, on what appears to be more or less random intervals, the router becomes unresponsive (it takes more than a minute to login) and everything stops working until I physically disconnect and reconnect one of the two ISP wan lines (it doesn't matter which one). It then instantly reverts back to normal, as if nothing happened. The only indication that there was a problem is an increase in activity (30-40%) for the "net background" process...

So far I've seen this behavior an all 12.4T releases from 20 through to 24.T1.

As such, I'm now using the 11.XW9 firmware which seems to be less affected by this than the "T" train ones.

At first I thought it was a high load issue, but as it turned out it can happen even if there is close to 0 network activity...

I really don't have any more ideas on this issue. Any help would be greatly appreciated.

Thank you.

Hall of Fame Super Silver

Re: 1811 router - high cpu load in dual wan config

Hello Matei,

you should post a filtered version of your configuration to get better help.

The router can have troubles with NAT entries for example rather then simply a traffic load effect as you already noted (random intervals even without traffic).

Hope to help


New Member

Re: 1811 router - high cpu load in dual wan config

Hello Giuseppe, and thanks for trying to help me out. Here's the complete config (minus the sensitive information)- hope it helps!

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