Recently changed to virgin media for my internet and then found i could not access my website at https://www.gcs3.co.uk at all, but if i switched off my wifi and used 4G or used a VPN I could connect no problem. After some faffing about I changed my wired pc to use google DNS rather than virgin media DNS and followed the guide here https://www.androidpolice.com/use-preferred-dns-server-android-tutorial/ so my wireless devices used google DNS rather than virgin media DNS. All works ok now. Really not sure what happened locally to cause this issue in the first place……release renew and flushing DNS didn’t fix the issue