Another thing, if it hasn't already been suggested.
Have you turned the router off and on again. Not the usual joke, this genuinely works well with routers for all sorts of fixes.
https://www.howtogeek.com/165110/do-i-really-have-to-unplug-my-cable-modem-for-at-least-10-seconds/
Wise move, starting with free or cheapest option first.
Tbh, if you're not running a load of devices and you're happy with the speed and connectivity on everything else bar this laptop, the Plusnet router might still be fine for you and you can save a few bob.
Hopefully, Barnet Seagull's...
Re: upgrading the bog standard Plusnet router.
Forgot to add. If you're on fibre, make sure that, if you do get your own router, it's fibre compatible.
Their supplied routers are bog standard. Definitely worth upgrading to your own. Looks like from your screen shot it doesn't even support ac but stops at n.