So weird. The only thing I know about networking is that the answer always turns out to be DNS (/s... I think? hrm, perhaps it really is the case? :-P)

Maybe someone else "near" you (in the IP sense) used a similar address that triggered blocking of the entire range that includes you.

Either way you could try playing around with a VPN, making sure to set it to a variety of different geolocations?

But the fact that it sometimes works - for many of us - while sometimes not working, for others, is definitely odd.