I know, I know, it sounds like a ThioJoe video. I assure you this is not.

Recently, I switched cable modems with my ISP. Let’s say this ISP was AS12083. In fact, I switched my cable modem over today! When I called customer service to transfer over my modem, it went over without a hitch, as the new config was transferred over TFTP to the new modem and rebooted. I unplugged the old modem and switched over to the new one. The first thing I noticed was that I was not receiving two public IP addresses as I did before, but that was not an issue.

During the night, I wondered what would happen if I connected my old modem back up to the coax cable and powered it on. Would it work? Or would nothing happen? I had to find out. I plugged the old modem back up, with the new one still connected, and connected my laptop to the old modem. After a few seconds, all the lights on the old modem were lit up and solid. For reference, the old modem was a SB6121 and the new one is an Arris TM822G. I connected my laptop to the old modem, and I received a DHCP address in the range. Whenever I navigated to a page, it would not load, and I could not ping anything outside of my laptop, not even the gateway it gave me.

After I established that I had no internet, I tried connecting to one of my ISP’s servers, which would display a message saying that the cable modem was not provisioned. This IP was, and sure enough, it loaded just fine! This got me thinking to maybe there was another way to connect to the internet. I tried pinging one of my servers within the same ISP. When I tell you my heart dropped when I saw the ping response come back as positive, it dropped.

When I found out that I could ping my server, which was on a public IP address on the same ISP, I got to thinking. What would happen if I tried to establish a VPN connection to this server? I pressed connect, and macOS said a connection was established. I tried going to Google, and it worked. I found a way to connect to the open internet without paying for service. I checked my server, and oddly enough it showed my laptop as a client with a 10. address!

However, there are caveats to this that I learned.

  • The only way to interface with the outside world was this VPN
  • The config on the modem limited my computer to 1 Mbps down, and 1Mbps up
  • There must be a VPN server with a public IP on the same ISP’s network.


  • Used an unprovisioned modem to technically obtain free internet access, although with some caveats.