I feel for you. I got sick of all this kind of thing. Mysterious problems with no solution, and hours upon hours of wasted time.

Since going with Mikrotik I've not had any issues like this. Plus the flexibility you get is unmatched.

If I take on a new network and there's a Draytek there it comes straight out and a Mikrotik goes in. I'm done wasting my time on these devices.

Today's update: A number of VOIP phones on our system are have been showing the wrong time - I suspect because the time servers that worked previously are not being resolved properly. Some VOIP calls have been good whereas some users have reported the person at the other end can't hear them - indicative of lost data packets during the call. I have also just run the DNS Benchmark on one of our networked PCs and over 20% resolvers were deemed unreliable. So similar issue to that reported by others in earlier posts. I will eventually try running a similar test through our modem on the WAN side to see what happens. I have also contacted Draytek customer support and await their diagnosis and cure!

apburden wrote: ...I have also contacted Draytek customer support and await their diagnosis and cure!

Good luck getting them to actually understand the issue...

I've lost hope in Draytek, went to Ubiquiti for wireless APs (just amazing!) and will be replacing the last Draytek router with Mikrotik. Really not worth the hassle with all the choice on the market.

We have had a very similar problem. 2930 with 2 x BT lines being used and DNS was constantly dropping out.

Tried automatically using the ISP DNS, fixed to use google and open DNS but the issue still kept coming back.

In the end we pulled WAN2 and everything worked fine, then Pulled WAN1 (with WAN2 back on) and DNS was problematic.
It would seem that the DNS issue was with WAN2 so we created a load balance rule to send everyting down WAN1.
Kinda defeats the purpose of DUAL wan but its working fine at the moment and other servcies are using WAN2.

If we get the DNS fixed on the 2nd line we'll try loadbalancing again and see if the problem comes back

the same is happening and with my 2920 and 2850
Had to set all load balance to one or the other wan but still from time to time fails on both but more at 2850