Article numbers are irrelevant to maintaining a connection to the news server.

On 5/27/2024 12:15 PM, Relf wrote:

My newsreader (Jeff-Relf.Me/z1.HTM) works fine with BlockNews because
it remember the last 10 Message-ID's, instead of relying on article numbers.
& This allows me to switch servers on the fly.

Article numbers are irrelevant to maintaining a connection to the server.
Blocknews drops/resets the connection all the time, and frequently won't reconnect.  Sometimes switching to another server then back to BN works, sometimes it doesn't and I have to restart the newsreader.
Eternal-september doesn't have connection problems.  It's just very slow to connect or download anything.

When stepping down to a lesser server (e.g. to Eternal-September)
it notifies me when the lesser server doesn't have one of the 10 Message-ID's.

"Lesser" because the admin blocked you for HTML in your posts?
I think ES is lesser because it's slower and has shorter retention/fewer messages.

Also, it notifies me when a Message-ID got leapfrogged
( because BlockNews couldn't keep up ).  See also:  News.US.Usenet-News.NET

BN kept up well in the past.  Betterbird and BN can be a pain to use lately.
Have you tried fastusenet?