You are likely experiencing an issue with missing addons/models/textures. Begin by installing all of the addons from our workshop collection: https://steamcommunity.com/sharedfiles/filedetails/?id=2141801591 If you do not have Counter Strike Source installed follow the instructions here: https://gmodcontent.com/ If you are still experiencing these missing models and textures you may have some corrupt addons.
This is an anti-griefing measure implemented to prevent users avoiding IP bans by the use of VPN/Proxy. The service we use to evaluate your IP when connecting isn't perfect and can sometimes raise a false positive. If you are experiencing this error and are not connected to a VPN or proxy please open a support ticket and we will add a manual bypass.