Running an Acer All-in-one on W10 (will not upgrade to W11) I found access to some sites (like Sainsburys and My account in the BT website though I could access the main site) was blocked. After various attempts to solve the problem, I disconnected VPN - and found I could access those sites.
At the same time the Fritz Box router I use through my ISP Zen was at odd times each day saying it was disconnected though I still had internet access. So far, having disconnected VPN, problem seems to have disappeared.
Anyone else have similar problems because of VPN ? And any way to use VPN without such side effects ?