Wifi Conundrum

Hi there

I'm using a Macbook Pro, Retina, Mid 2012 with MacOS Sierra version 10.12.6.

The macbook pro connects to my virgin router for wifi. It has done so without problems for years. Suddenly it has started having problems connecting. The wifi icon in the menu bar displays with the full 4 bars suggesting it is connected, however there is no active connection. If I share my iphones 4G signal via a hotspot with the macbook pro when it is displaying this problem, the macbook connects to the hotspot no problem and I can load web pages etc. My iPhone, iPad and ASUS Zenbook laptop with Windows 10 have no problem connecting to the Virgin router and using the connection.

So it would seem that the Macbook pro has a particular problem connecting properly only to the virigin router now, although it can connect to other wifi, and other devices can connect fine to the virgin router.

The problem has persisted intermittently for the past week. If I shut down the mac and restarted it the connection will start working again for a time, then will eventually stop working on the macbook pro even though the wifi bars are still all lit up on the menu bar. I have also re-booted my virgin router by disconnecting it from the mains and re-starting it to force it to make a new connection, but there has been no change in behaviour on my macbook pro so far.

Not sure what all this means, would anyone have any tips as to how to troubleshoot this problem?

Thanks

Colin