Do you have access to your server logs? If so, try watching the logs:
tail -f /path/access.log
tail -f /path/error.log
/path/ is your full path.
You can also try to trigger a DHCP refresh on your home IP address. My home router lets me do this, or you could try power-cycling your cable (or DSL) router. Sometimes it'll get you a new IP address.
As an aside, I'd also sometimes get completely blocked from my site(s) during heavy development cycles – no http, no sftp, no ssh. And then it'd clear up. My hosting provider said they couldn't find anything, but I suspect it was on their end. Probably something that got triggered by all my various accesses to the site in a short amount of time. Using my cellphone as a hotspot, as you did, got me access.
