The unfortunate truth is that it's somewhere between you and the server. The server doesn't randomly add firewall rules either I fear (and I checked a few IP's before and did not find them).
Turning your router fully off for a while and back on might reset the IP and get around it.
Alternatively you could try asking the provider I guess...
The odd thing is, players affected by this don't seem banned by our host or anything like that (http://supermechs.com keeps working just fine), it isn't tied to the domain either nor does it seem in any way like it origins from the server (nor would that make sense).
We're not on any blocklists either, at least, no online ones..
Edit: The other vocal person affected unfortunately didn't have cmd available, since you do, would you mind pinging and running a tracert and sending the results? It'd help!