As stated, the link you have in the vanillafix.cfg file, as well as posted on your Curseforge page has been dead for at least 3 months now. Whenever someone tries to use the Get Report Link the website returns an Error 504 on cloudflare stating that the host is where the error is happening:

Is there any plans to either resolve this issue any time soon, or should we modpack authors and server owners start manually changing the preset link in the config to something that is actually working?

The domain is parked now

Related to (possible duplicate of) #262

I wish people could like change the site to something like Pastebin

Related to (possible duplicate of) #262

It is related to, however now instead of a 502 error, it is kicking a 504.
A 502 error means that the gateway itself is bad, or has bad information. A 504 means the gateway is there, and or the information is good, but for some reason it is taking too long to respond and deliver the information. These are two different problems and require different steps to resolve them. This is why I started a new thread. While they are related, they are also different.

The exact HTTP error seems to depend on not only the time of access, but also the location where you tried to access the website from, since I'm getting HTTP 502 (instead of 504) accessing the same website.

Resolved. Went into the server and did some asking around. Thanks to the user Snowie the site: https://paste.dimdev.org is back-up again! Also all previously uploaded crashes are accessable again! Not the onces between now and when the site went down.