Wireless connection problem: "cannot connect to this network" message

Hello,
My desktop PC cannot connect wirelessly to my router. I get the message "Cannot connect to this network". The adapter driver is up-to-date and is shown as working properly. Other devices connect wirelessly with no problems (including the laptop I am using right now with same OS = win 10 Pro 64).
The motherboard wireless adapter is a new type (Broadcom 802.11ac) but my router is the older type (B/G/N - Mixed Mode) - are these two should be compatible (even if not working optimally) or should I get a router 802.11ac?

Thanks for your help,

Collpicto

Is the router set to n type in theory it should be able to connect but there is a massive difference in speed as AC is up to 3gigs so there could be a problem syncing with the router. Routers are like PC's an old one has low CPU specs compared to new ones it's like an old 486