That's a fun project. But I wonder: is it a good idea to connect to the internet from these old systems?
I expected the installation to be infected very quickly, but seems it just got a bunch of port scans and not much more than that.
These days ISPs are better about shutting that kind of thing down. They monitor for botnet activity in their networks and their modem/router gateway combo devices are a lot more robust than they were in the 00's. It is also more acceptable now than it was to ship routers with upnp turned off by default, which helps A LOT.
For example, I'm paying double the local market rate of a 1gbit connection for ~150-300mbit connection, and I can't even change my WiFi password or SSID. That's just how everyone expects renting to be these days. It's not worth the hassle to fight it, so I just hack around with tailnet instead.
Security by 'obsolete' !