It's a problem that does not affect everyone. As someone who has been on the receiving end of it for almost all of Stormblood it's a problem on Square's end, namely their ISP NTT. Unfortunately all you can do is wait it out or use a VPN because Square "will not" talk to their ISP about it but rather tell you to talk to yours (which isn't where the problem is). Only some routes on NTT are affected which is why only some people experience this problem.

It's still going on right now but it's not as bad was it was a few hours ago. Not to be the bearer of bad news or anything but if it's been an issue for nearly 3 years I wouldn't expect the problem to stay permanently gone. At least it hasn't happened consistently every single day around the same timeframe like it was in Stormblood.