Many people have posted (on various forums) and hundreds have read about connection problems with 2.3.0

I found that I had to delete the contents of my Bearshare folder
(excluding the TEMP and DOWNLOAD folder) before reinstalling 2.3.0. It helped me bit, though connections are still sporadic and horizons are still poor. I have often had horizons stuck on 1 for long periods of time before the connection is lost. Other connections are cancelled immediately for no apparent reason (no, they weren't duplicates.)

I won't pretend to know what's going on, but I assure you I had much better luck connecting with 2.2.7