Looks like the cause of this is commit #fb473a7 included in v4.23. Android and Windows clients connect to Linux and Windows dedicated servers without any problems. iOS clients refused to open connection to both Linux and Windows servers. We tried mobile internet with server in the cloud and local …

Thanks, I’ve entered this as Unreal Engine Issues and Bug Tracker (UE-81740) Edit: This should be fixed in 4.23.1 - let us know if you’re still having troubles