"Download Error" Upon Start-Up

OS: MacOS Big Sur Version 11.3.1
Launch Version: WesterosCraft 1.12.2 Production Server
Issue: Upon launch, launch aborts during download phase. Gets error message saying "Download Error." I've attached an export of the console showing the error.
Explanation: Application used to work well for months. I haven't logged in a few months, and this is a new issue. I reloaded the Launcher to be safe and it didn't fix. I saw in a previous post that it may be related to my "router firewall." I have the Xfinity high speed router, and I don't know how to access it. Any suggestions welcome.
Hi Luk:

Sorry for my delay following up. I got swamped with work. The link opened into a text-filled screen without issue. The download is still blocked, though, alas, when I try to join the server from the launcher.


I figured out how to access my internet router. However the firewall appears to be disabled and set to not block any application or traffic. (Makes me glad I have security on my laptop itself) I'm curious about what else may be blocking the download (other than potentially the aforesaid security on my laptop itself).