All of a sudden my 2820 has stared lying about the IP address of some websites - well, rather it has started saying it can't get to them, when a LAN connected (or WiFi connected) PC tries to get there. The most noticeable one was 'members.ratesetter.com'. The Router was set to be a DNS proxy (nothing filled in for LAN DNS serving, so PCs etc picking up 192.168.1.1 as DNS server address), and it was obviously not sending requests off to the ISP DNS server(s). A tracert from the router control panel worked fine, a tracert from a PC using the IP address for that site worked fine, a tracert from a PC (or tablet) using the URL got me 'unable to find the site'.

Rebooting the router =sometimes= seems to fix it, but not always and not necessarily straight away. As a temporary measure I have inserted the ISP DNS server addresses into the LAN config, so PCs etc should pick those up and the DNS proxy will not get invoked, but that's a bit a a kludge .. is there any way to restart the Vigor 2820 DNS proxy, flush its cache, or even collect some debug info to see why it was giving 'can't be found', probably without even bothering to look? Possible the lack of a 'www.' prefix is annoying something, or maybe the router is just, like, me, getting old?? 8>.

I have never heard of such problems, are you sure it is not your local PC which is getting messed up? What are the upstream DNS servers your Draytek is set to? Have you tried the latest firmware?

If you have a corrupt config etc then you could be getting CPU/memory exhaustion and DNS may be some of the collateral damage, so personally at this stage rather than complicated diagnostic I would update to the latest firmware using .RST file and redo the config.

As I said, it is not my local PC since connected android tablets and wired/wireless laptops are getting the same DNS error from the DNS proxy. It could be cpu/memory issues, since I have been issuing a lot of web requests to very long URLs (e.g.
www.xyz.com/datafeed/?abc=13&abc=23&abc=56& ... abc=1322 where '...' may be 300 or 400 characters) recently Problem goes away if I force a different DNS onto the client machines too... only an issue when the query the Draytek DNS proxy.

I Will try the latest firmware and see if that helps (plus a power cycle on the router, although a reboot ought be enough).