It is the Global Server Workaround which is causing Discovery to deny connections! It looks like the anti cheat is stopping other servers because if it detects any additional dlls added to the dacom.ini file then it will not connect. I did no other mods or additions other than the GSW and when I manually added the 2 dlls needed to the dacom.ini file Discovery disconnects instantly that I connect. Before adding those two links to that ini file I could connect and play it. Therefore it looks like the developers are determined to stop other servers from working. This did work when I used this shortly after I started playing Discovery. It's no wonder people are rejecting how Discovery is working now and stopping playing it. I will think about this and as it stands I am highly likely to stop using it myself. I have been considering moving to other mods and the Russian one looks interesting. Or move to other more modern space games which I have a few.
Thanks to those who tried to help but unfortunately the developers have stopped it from working.