One of the replicas is currently experiencing a lack of disk space, if you are able to, please hard-code the IP address to 193.62.202.30 when you get a 404 message.
Unfortunately snapshot.debian.org uses name based virtual hosting, so you can't simply use the ip address in the url. Putting it in /etc/hosts would probably work if you have root. Otherwise you need to find a way to convince your http client to use a user-specified ip while still sending "snapshot.debian.org" in the host header. I implemented python code to deal with this situation in https://github.com/plugwash/autoforwardportergit/blob/master/snapshotsecure