Well, I tried again tonight and the whole network still has my IP address on ban. It's been suggested that someone else had had this address (under DHCP, as I do) and got THEMselves banned, and I have nothing to do with it. However, as it IS cable, and it feeds the whole house's wireless network, I'll have to remember to try to release/renew and get a different address at some point in time when nobody else is on, and won't be disrupted.