502 failure out of left field

[firehousefourfiveone]

Hi - long-time user but still feel like a newbie about many topics. Recently started getting 502 "server rejected your login" with one of my three servers on v6.90. My subscription is still good and the exact same address and login credentials still work fine with other newsreaders. My other servers are working fine.

The problem started after I tried changing the server in question (newsgroupdirect.com) to its other regional servers to check for improved retention. In the middle of this experiment is when I started getting the 502 error.

This problem persists after I completely removed the server from my list and reset the server, being careful to fill in the exact same info that is working fine elsewhere. I'm stumped - any thoughts?

Thanks and cheers