We have a Vigor 2862 at a remote site connected via VPN. To resolve local domain DNS i have a forwarder setup to send all DNS requests to domain.local over the VPN to the DNS server IP. This has been working fine for months but has recently started to be intermittent and i dont know why?

I have rebooted both ends of the VPN and upgraded firwmare but still the same. If i use NSLookup the DNS request works fine but the forwarding fails. Occasionally it will resolve one DNS request but then fail on a second request. The ping times between the sites isnt great (over 200ms) so i wonder if the forwarded requests are timing out? Can anyone think of anything i can try?

I presume a local authoritative DNS server for "domain.local" is out of the question. If this is a Windows AD network, then (grimacing at the 200ms rtt) the domain functions at the site would also see a general improvement.