Hi, I worked a bit in this and think I might have come up with something. I happen to have a spare Pactor modem (bought it cheap
in a second hand shop). When I plugged that in it worked fine. So I went back to my IIe (not a IIex as I thought). I checked the firmware and it was 3.3 and the latest was 4.0 (which my spare was already at). So I went ahead and flashed it to 4. It then connected and worked as it should. So, not sure if it needed the newer firmware or somehow the old got corrupted somehow. Anyway, fingers crossed that this solved
The reason I suspected the modem was that it would receive a very clear transmission. It would then act as if it had not and request a retry. Very odd.