Here is the way to "veto" the troublesome servers so you can have a reliable ladder practice environment.
This trick has been in use for over a year by more than a dozen players with zero issues.
How to setup the great emu wall:
1. Open 'Windows Defender Firewall'.
2. Click on 'Advanced Settings'.
3. Right-click 'Outbound Rules' -> Create new rule.
For the rule you have just created:
-Set the rule type to custom.
-Set the program path to your sc2 executable (try setting it to C:\Program Files (x86)\StarCraft II\Versions\<Latest Base Version>\ ).
-Set Protocol type to Any
-Under scope, add the following REMOTE IP addresses:
18.104.22.168 to 22.214.171.124,
126.96.36.199 to 188.8.131.52,
184.108.40.206 to 220.127.116.11 and 18.104.22.168 to 22.214.171.124
-Set 'Action' to 'Block the connection'.
4. Under 'Inbound Rules', delete all of the SC2 entries (this may not be necessary).
5. Start SC2, but do not click "Allow this program through windows firewall". If you accidentally allow it through,
go back to the previous step and delete the entries again.