>(even though the claim is that your IP is dynamic, in practice it hardly ever changes)
Every ISP just uses DHCP for router IPs. It's dynamic, you just have to let the lease time expire to renew it.
Or, have your own configurable router instead of the ISPs so that you can actually send a dhcp release command though they don't all support this part. Changing MAC Address will work otherwise.
When the lease expires, the same IP is prioritized for renewal. Leases are generally for a week or two, but I've noticed dynamic IPs staying for 3 months or more. Swapping modems is really the best way to get a new external IP.
Every ISP just uses DHCP for router IPs. It's dynamic, you just have to let the lease time expire to renew it.
Or, have your own configurable router instead of the ISPs so that you can actually send a dhcp release command though they don't all support this part. Changing MAC Address will work otherwise.