Unity connection issue mac; cannot join servers

For starters, I'm not developing any Unity projects, I'm on the consuming end for now, which doesn't make this any easier. The issue is, several Unity-based games seem to refuse to connect to any set up game servers the list may provide, and I do not understand why.

For clarity, I will use the game Intruder as my common example.

When on my laptop, I have the same thing as on my desktop; I can log in and reach the server list without problem, and whilst there receive accurate information on the servers' player counts, which suggests communication has been established. However, once clicking on, and selecting a server, which normally would send me straight into the game, the menu briefly freezes up, then unfreezes, and proceeds to do nothing for longer than I have patience to wait for. I have several times attempted to leave it in this state, running in the background, for hours at a time in the hopes of seeing change, though to no result. The same issue appears at the same stage of different Unity-based games, including Project Stormos, by the same studio as Intruder.

I have spoken to the developers, and they seem to suspect it to be an issue with 'photon', though they do not know what might be causing it: My ports are open, and their own tests on their macs yield no such relatable issues whatever they try. We are, somewhat, at a loss.

Personally, I don't even know what this 'photon' is, precisely, and none of my searches have uncovered any issues that seem relatable, no matter how I phrase it.

Thus, I write to these boards in the hopes that someone who reads this might have an idea of what I could do next to, if not solve this issue, at least begin to get a better idea of what the issue itself is. What could my next step possibly be?

In high hopes,

     ~Glun

Fun fact: Restarting my desktop computer into windows and trying the windows build of Intruder goes without hitch: I have no issues there whatsoever. This fact mystifies me no end.