Can't access github.com with my home wifi

Hi, I am not able to to access github.com (or any other urls of it) when I am using my wifi at home (the page doesn’t load - get a timeout error). When using my phone as a hotspot I am able to access it.
I’ve installed the wifi (the network is Virgin Media, I am in the UK) in my house a few days ago, however in the last days I was able to access the website, I didn’t change anything today that might explain it. Firewall on my Mac is not active. I tried restarting the router and the computer but that also didn’t help. I am encountering this issue only with github.com, all other websites work. Would appreciate your help, thank you!