Yes it is possible, many possibilities from 'accidentally' deleting rules and ip networks, or wrong security patch applied to the router, and all other human errors, but this is not a small company NOT to have a backup (hardware or software) to restore from the original config. If we are talking 'router' issue, most hosting companies were configured to multi-connect from one to many links, so if one device failed the remaining active devices will provide the service.
If they identified it is a router table issue, I'm surprise that it was not restore sooner. The monitoring software can tell you if a device is not responding. Oh well.