> If you get an nginx page (I seem to get one pretty often)

It appears to be a rate-limit mechanism of some sort specific to a fingerprint. Clearing cookies for archive.[is|vn|fo|md] may (or may not) get you past it.

I'm pretty sure it's IP-based because I get it on different devices from the same network when it happens.

And make sure your DNS is not 1.1.1.1. Archive.is will alter requests coming from their DNS. They do not always detect it.