Not knowing who your isp is it's going to be general help and the first thing I'd normally try would be to turn off the router/modem for 10 minutes or so then restart it.
This not only restarts the router but with many isps who use dynamic ip addresses it should also assig you a new ip address.
It's always worth checking PlayStation network service status at https://status.playstation.com/
and your Internet Service Providers service status page in case there is an issue at their end.
