What could have changed to make my connection closed?

A few weeks ago I was able to send the link out fine, people could connect, and it was no issue.

For some reason, when trying a few days ago, I get the “your connection appears to be closed” message.

I’ve done some troubleshooting, and have tried to set up port forwarding using the foundry website guide, but to no avail.

What could have changed, and are there any other solutions? I am just really unsure why it even happened, and why any solutions like port forwarding and allowing access through firewall are not fixing anything.