We also have a 3300v that regularly freezes/locks up. Only fix is a power cycle.
Does anyone know which firmware version is reliable?

Hi,

None of the downgrade firmware versions worked on our new broadband line, in the end I had to replace the unit with a Vigor 2955 which has been running fine for the last month and a half now. Not ideal, but I was going round the bend trying to get Draytek support to fix this problem - they were sending me tweaked firmware upgrades, going through the log files but couldnt work out what the hell was going on...I gave up in the end.

Sorry for the delay, We found that Firmware Version : 2.5.9.0 (EN) works best. Had no lockups since downgrading to this.

Cheers. I'll give that version a go and see how we get on. If this doesn't work I'm going to look at replacing it with a Fortigate box, possibly a 80c or 110c.
Anyone have any experience of these?

No experiance with Fortigate. What does the device need to do?

Looking for an enterprise class firewall (UTM) with vpn facility to replace the 3300 which was originally purchased for load balancing but this is no longer the main requirement.