With remote access, it’s not just about your own server and router configuration but also your ISP. So even if you didn’t change anything, there can be some change along the chain of communication that’s now impacting your setup.
I generally recommend to have a look at this troubleshooting guide to identify what might be going on (and some potential fixes). In some situations, there’s nothing you can do but go to your ISP and asking them nicely for… well… that kind of depends on what they did
