Lagging like crazy, possibly due to wifi? PS4

Hi, for the past 2 days my Overwatch has been unplayable. My latency sits at around 30-50MS usually but it has been going from 40 to 70 then back to 40 pretty much consistently, no huge lag spikes. I connected to my phone hotspot and the lag got considerably better (even though latency was a little higher) so I assume the problem is therefore with my wifi?
I have reset the router, re-connected the wifi extender and done a speed test. Absolutely nothing has changed, still running at the same speed as usual, is absolutely fine on other devices just Overwatch is being ridiculously laggy. Not sure what else to do?

It does sound like your WiFi might have an issue. Have you tried any of the other steps in the sticky thread?