WSS Agent was in Turkey but was not connecting to GTRAN11 (Ankara, Turkey).
WSS Agent 7.3.1
Support for Localization Zones started in WSS Agent 7.4.2 (WSS Agent Release Information).
Localization Zones are explained here.
Upgrade WSS Agent to 7.4.2 or higher resolves the issue and WSS Agent can connect to closest Data Center, even it is a Localization Zone.