Hi @TheRealMuffin and welcome to the forum.
Looks like the connection attempt gets refused from the Roon Core (MacBook Pro) [SocketException (0x80004005)].
Main change that might cause such an issue was IIRC a change to encrypted connections with Roon 1.8. This could be a firewall issue on the server (read also: McAfee complains right after update to Roon 1.8 (Build 806) stable (64 bit) [Answered] - #3 by dylan) or your Linux box is using outdated (old, unsupported or flawed [generating insecure keys] encryption libraries) or something like that.
You should contact whom ever is responsible for that machine and discuss the issue with them too – especially if you can rule out problems with the server as the cause. Keep your 1.7 Roon Bridge installation until maybe you can find a solution or the Roon Core refuses unencrypted connections altogether (this might happen at some time in the future).
Disclaimer: Not official support - just another Roon user.