Wv> When I try to connect to a particular "Mystic/1.12A34 binkp/1.0" system,
 Wv> all I get is this:
 Wv> 
 Wv> + 24 Jun 20:57:40 [30502] call to ***
 Wv>   24 Jun 20:57:40 [30502] trying ***...
 Wv>   24 Jun 20:57:40 [30502] connected
 Wv> + 24 Jun 20:57:40 [30502] outgoing session with ***
 Wv> ? 24 Jun 20:57:41 [30502] recv: Connection reset by peer
 Wv> + 24 Jun 20:57:41 [30502] holding *** (2017/06/24 22:57:41)

 Wv> Is this a known problem maybe? Or what could it be?

There aren't any known issues with Mystic's BINKP at the moment.

Are you able to get a log from that system from the Mystic side to see if
it reports an error on its side?

What software are you using?  I know there is some issue with someone I know
who has a BBBS system where his system keeps polling Mystic over and over
(but Mystic connecting to him works fine).

--- Mystic BBS v1.12 A35 (Windows/32)