Hi all
I have a Vigor 2820 router as our gateway for our company. It is fairly new (a couple of months) but has recently been losing our outbound web connectivity.
Inbound internet access is fine (forwarded ports to email, web server , VNC, etc.). Outbound non web acces is fine (VNC, outbound links to IP addresses, etc.) but nobody can access web pages using domain names.
This is solved by rebooting the server. I have tried just dropping the internet connection and reconnecting but this makes no difference.
My limited knowledge suggest that this is some sort of DNS problem but I have no idea where to start.
I have written a script that PINGs Google every five minutes and if it cannot find it then it reboots the server but that is not ideal as it means the connection has gone before anything is done about it and it takes a fair while to reboot and reconnect to the internet (almost a minute).
Does anyone have any ideas what might be causing this?
Many thanks in advance.
Mike

When you say server do you mean the router?
That could be caused by the DoS protection on the router if it's cutting off DNS after a few minutes - you can fix that by checking under the Firewall menu then DoS Defense, usually what triggers it is UDP Flood defense, either try disabling that or the whole DoS defense.
Also, if you've got syslog set up on the router, that'll show if it's actively blocking DNS or if it just stops working.

Thanks for the swift response Voodle. Of course I did mean router but my hands didn't agree with my brain!

My DoS UDP defence is set at Threshold 150 Timeout 10. Which way should I change these as I can't get my head round the + or - :?
Thanks
Mike

Either turn it off or set the threshold up to 1000, it may or may not be this but it's worth trying this first of all, if not then look for the 3.3.4 RC10 firmware in the thread about the lack of firmware updates in this forum.

Thanks Voodle,
I've disabled the UDP defense and I'll see how it goes.
regards
Mike

really did my nut in this. router wiped and config reloaded. turned 2820 off for 10+ mins at a time somtimes. some pc's would work if you edited there local host file. others just woudnt work. server restart everything worked fine again apart from the last time it happend. issue can last from 10 mins to 9 hours.

i turned tuedn off udp, not had the issue since.