Hello DC-Talk! This thread is mostly created to help europeans, since official modem list is mostly US centric, when you consider the shipping costs, tax, customs fee and delivery time, modem purchase can turn away some folks that want to go online with their DC. Another reason could be that modem from Dreamcast Live is not available.
These modems were used in conjunction with this PC-DC server guide by megavolt85
Easiest and less time consuming option is to buy from Amazon DE. ASHATA USB 2.0 Ethernet Adapter Dual Ports USB to RJ11 Gigabit Network Adapter Support for Win 98/2000 / ME/XP/Vista / CE5.0/10 / 8.1/8/7
Manufacturer : ASHATA
ASIN : B07WW3L3QD
Item model number : ASHATAgw73k06snm
This modem supports all AT instructions that are required to connect your DC to internet. It works the same as modems from official modem compatibility list.
Option two, Trust MD-1250. Very cheap modem that requires some fiddling with it, because it doesn't support half of the instructions needed, but it still works, if you follow the instructions. Basically you need to use Scrivani's custom script.
Product page
Simply swap dreampi.py file located in /usr/local/bin/dreampi and rename the given script. If your connection is not stable enough, open the script and find given values and swap them. From 57600 to 38400. It will change your baud rate and fix instability.