I have got through 7 Vigor 120 modems in the last few years, across two sites. They just start dropping connections. A reboot usually brings them back for a few hours. Replace, and all is good for a few months.

Had a couple replaced under warranty, purchased a few.

Is it just me finding these fail?

Using with 2820 and 2830 routers.

There have been more failed units than might be expected; the symptom is the LAN port failing or intermittent. They can be replaced under warranty (which is 12 months, but they're flexible )

That makes sense, I think removing the LAN lead and putting back in often cures the problem for a few hours.

Think I want to try something different. I can't keep swapping them out. Was the old 100 any good?

The Vigor100 was the same spec, but the Vigor120 is excellent; new units don't have the problem - it was only units shipped in 2012 that saw a spike in problems I think, and only a minority of units develop problems. The problem tended to show up about 12 months after they were put into use (and with a 12 month warranty, which is why they informally extended it if you had that problem).

10 out of 10 failed for me....some sites more than once....

That is extremely unusual and may be some additional factor, especially as the replacements also failed because replacement units had additional changes to resduce the chance of the same problem (unless it was very early before the problem was realised by the engineers - i.e. that is was a significantly unusual rate, necessitating a mod, rather than odd ones..)