Been suddenly facing this problem the whole day with my PS4. I cannot sign into my PSN account. I can connect to the internet and use the browser. If I try signing into PSN or opening the store, it takes forever and the request eventually times out. If I try a connection test all the parameters are fine apart from the PSN login, which immediately fails (it doesn't even take a few seconds to attempt a login).
Here's the tricky part - I share the console with my brother. If I switch over to his user, there is no problem and it signs into his PSN straight away. The problem only occurs on my user for some reason, which makes me feel like it can't be an ISP/router issue.
Any help would be great. Thanks.