All STEAM server needs to be update since yesterday, otherwise the server will be pop-up a warning message something like…”Please update and restart the server”. If you ignore this warning, your server will not be listed on the master server list.
The new version was 4381 for windows and for linux it was 4352. It has also changed the protocol from 47 to 48. Therefore, the old version client can not connect to the new server anymore unless you update the new version. It means that the old version of non-steam client could not getting into the new version server. The new version of client can not join the server which hasn’t been upgraded as well.
Those servers which are hosted by wallaceho.com has been prompt upgraded to new version. However, there are still have many server which have not been upgraded till to now, for example: hkspirit
The new version of client has added many functions, one of it is while you showing up the score board, you may saw the photo of your friend list.