I’m not sure if this has to do with their “decommissioning” actions, but I have been having issues connecting and checked their list of networks to find an alternative server to the Librem.one default of us-california. Since us-east is closer, I switched to that and was able to log in.
As for connecting to their “more advanced and highly upgraded Gen4 Network(Next Generation Network)”, they have a 64-bit Linux client, but I doubt it’s open-source.
The downloads page also has “OpenVPN Configuration Files” toward the bottom of the page. I’m not an expert on these things but I couldn’t get it to work—I was getting authorization errors, so I figured our authorization information was not valid on the new network.