A family member is staying with us for a few days. They bought their laptop (older Lenovo Ideapad 320, model 14-AST), which connects to our WiFi (Fritzbox 7590 / 2degrees fiber) and they can browse most websites on the web fine. Stuff.co.nz, NZHerald, Facebook, they all work no problems.

There's one NZ website they access regularly that works fine on their computer at their home but wouldn't work our WiFi, but that computer can access it using ethernet. Every other computer / phone in the house can access that website on WiFi or ethernet. Oddly that computer can access the site using WiFi when tethered to my Android phone.

Another odd thing: when plugged into ethernet the computer can ping the website by domain, but when it's on WiFi it can't ping - though the DNS resolves to the same IP. Again every other device in the house can ping on WiFi or ethernet.

Can anyone think of anything that would cause this laptop to not be able to access this one website when on WiFi, but be able to access it when on Ethernet? I've reset windows, installed drivers from the Lenovo website, updated Windows, everything I can think of, with no change.

NB: I haven't named the website because it's related to gambling - very low level and common, but still gambling.

Update: As per post below, IPv4 isn't working properly on the computer but IPv6 is. The website that isn't working is only available on IPv4.