Any experience/opinions of Draytek Vigor 120 modem long line

My Billion 7800N cooked itself during the hot weather which was a shame as it seemed rock solid on my line which is about 3 km though had to have 3 replacements for various defects in 12 months.

Replaced it with a D-Link DSL320b modem and Netgear JWNR2010 router to separate the functions in the hope of cutting down heat accumulation.

Trouble is I'm not getting random connection reset/cannot find server messages.

If I lower the MTU from 1492 on the router some pages like this just won't load.

Not had to mess with the Windows MTU before so fiddled about last night and set the modem to PPPoA with my Zen user ID and password on there, raised MTU to 1500 on the modem and configured the router as a fixed IP client/DHCP server and set MTU on that to 1500.

When I came home I had to reboot the modem as it had lost PPP and it looks like the sync rate has dropped.

Asked on the Zen forum and here about the chipset used in their DSLAMs but they are remaining tight lipped.

Reluctant to switch back to a modem/router but was wondering if the Vigor 120 modem is comparable in performance terms with the 7800N modem on long lines before I buy one?

How about a HG612 from Ebay?

Thought these were VDSL?

As supplied by Openreach. However, if you unlock it you can set it up for ADSL

Will have a look