I have been troubleshooting this issue for a week now - following suggested solutions for problems similar (although not identical) to mine, to no avail. I believe I have finally narrowed down what event is causing my internet connection to be unavailable.

When I log in to my Windows 10 desktop my internet connection is unavailable to everything. It does not matter whether I use Ethernet or wireless connection. If I start up the desktop and just leave it sitting at the sign in screen, everything is okay. The desktop shows it's connected. I can connect and use laptops, TV's, tablets, phones, etc. The first time the internet is accessed via the Windows 10 PC it will occasionally last5 minutes or so, but mostly drops out immediately.

As I said I have done most recommended suggestions I can find - e.g. changing modem/routers, updating adapter drivers, switching off firewalls, changing browsers, swapping cables, etc. etc. That many, I can't remember them all.

Can someone please offer help - I feel I am going around in circles now.