Thanks Budman @Bazza I've now copied the text from that link and it should be below
HOW TO GET COD4X/MULTIPLAYER WORKING 2022 - NO MANUAL DOWNLOADS/PATCHING REQUIRED
HOW TO GET COD4X/MULTIPLAYER WORKING 2022 - NO MANUAL DOWNLOADS/PATCHING REQUIRED
Edit : Don't click the links in the comments, this is for windows only, you do not need to manually download any files
1) Install CoD4 from steam
2) Launch multiplayer
3) Enable console in settings
4) Open console with Tilde (`) key
5) Manually connect to any C4S server by typing one of the following commands into the console
/connect 178.33.157.21:28958
or
/connect 178.33.157.21:28953
6) The required files will download and you will be prompted to downgrade your version, click yes to any box that appears
7) Relaunch cod4 multiplayer, you will now see Cod4x 20.1 or higher in the bottom right
after clicking join game ensure source at the top is set to "Internet COD4X"
9) Done, multiplayer is back!