Turtles and neurals work fine. Computers only receive a subset of modem traffic (possibly some other related issues as well as GPS seems to be non--reliable lately.

To test: I opened port 999 on the modem and listened for traffic (on the switchcraft server, about 25 computers send out a beacon on that port every 10 seconds). The computer was only able to see traffic from 8 computers while the turtles and neurals can see 25.

I've gotta say, this is the weirdest bug - the code for computer-based modems is pretty much identical to that for turtle upgrades or neural interfaces. I'd understand if it wasn't picking up any messages, but some of them? Odd.

Kepler also mentioned that "turtles with standard modems were no longer able to get GPS positioning". This is probably related, so worth looking into at the same time.