since I upgraded to 3.3.4 had instability problems too. Random reboots, sometimes with a complete lockup requiring a power cycle.
Done some testing and found that if I disconnect the ADSL the router is stable (Virgin media DHCP on WAN2).
will be reverting to 3.3.3 if possible

if it reboots like that, go into the router's telnet interface and get the output of "sys ver dbg" after its restarted (and not power cycled) and send that to draytek support, that's the quickest way to get the bugs sorted for the next firmware.

I upgrade my home draytek 2820 to the latest firmware and it all went fine (well no rebooting loop anyway..vpn is flaky now and mOTP worked once! - seems like the vpn issues came back like they did in the last bios update where i had to ping -t as the router would kill the vpn but windows would stiull think it is connected. )

edit: the ping -t doesn't stop the vpn dropping this time...

I then updated the bios on the office draytek (whose bios was at 3.2.0) and it said it had completed successfully and rebooted. It then never came back...and I updated it manaully...

A 50 mile drive later, I got into the office and found it rebooting. the 3 vertical lights in the set of 9 on the far left of the router would light up...flash a bit and then it would reboot.

I tried the factory settings reset on the front and turning it off - but it still rebooted. I then unplugged all cables from the front and was setting up our old adsl modem to get the office online again - when I saw the router was sitting there not flashing just looking normal. I plugged it in to the adsl line and hub and it was all fine. It even had all the correct settings still.....not sure what was going on.

cbsys wrote: another 3.3.4 issue-

You cannot access your router's WAN IP from inside the LAN!

Yes, I have this issue too. Reverted to 3.3.3 and it's working again.

Mike

cbsys wrote: another 3.3.4 issue-

You cannot access your router's WAN IP from inside the LAN!

Is that just a 3.3.4 issue? The old 2800 had this problem I think and I managed to work around it though I forget how. I have just hit this issue trying to access a DMZ host from the LAN through its WAN IP.

*edit* nvm just read the above post.

Also my 2820 has periodic bouts of massive latency on its LAN interface, seems to coincide with the relay inside the router clicking, which apparently it should not be doing in my setup.

May downgrade to 3.3.3 if people are generally happy with that version, I never tried it, I upgraded as soon as the router arrived.

upgraded a 3 day old 2820vn from 3.3.3 to 3.3.4. i now have the rebooting loop.

I have done a hard reset on box and tried to downgrade it to 3.3.3 again with firmware upgrade utility.

I have held the reset button while powering on and got the three far left leds flashing together to show that it is in TFTP mode but it will not connect on the firmware upgrade utility.

I have checked that it is at the factory address of 192.168.1.1 with a mac scanner and it is.

Not sure what i can do with it now.