I've managed to add Amiga500 to network using RS232 ( a request from fellow Amigist).
It works with mikrotik 'hap ac lite' router (~50eur), USB RS232 dongle, AmiPPP, AmiTCP.
First you need to connect everything, then disable 'serial console' on router usb1, so that you can add ppp interface on usb1. Its pretty much straightforward from there on, if anyone needs details, will post them.
Sounds like you'd need to be a 'serial' masochist.....Pun intended. But each to their own.