I never reported the webpage not being able to load, and like I mentioned in the original post, all of the users were connected to the internet and in some cases had better internet than I did. Still had issues. I've never had the issue before when dealing with Construct's multiplayer, what changed? If it's not Construct's fault, did something change with the system it relies on? If so, it might be good to find a better way to implement multiplayer if it's susceptible to just... not working for any reason.
Your best bet is to find any error messages in the console or similar. Antivirus software or the Windows Firewall could also block outgoing connections on NWjs desktop.
TheRealDannyyyThanks for providing your input. I suppose realistically if I want to pursue multiplayer or help another user pursue multiplayer (as it is in this case), I should probably use a third-party plugin or just not use Construct entirely. I really appreciate it.
The mentioned peer-to-peer connection issue could still affect your game, regardless of it being off-topic. The plugin is not to blame for this though, it's a complex issue with the Internet and certain networks in general.
The grass might look greener on the other side but other engines often come with multiplayer issues of their own. I know it's a bad situation right now but there is not much that could be done, without finding the actual cause for your issue.