Hello Mohd,
Thank you for your message.
Our servers are running with 100% uptime recently so it's definitely not the server's fault. The most obvious reason why your Host cannot connect is a firewall problem, namely blocked outgoing ports which are used by the Host.
You can find more information about the ports in this documentation article
https://www.remoteutilities.com/support/docs/ports-used-by-remote-utilities/NOTE: the article mentions version 6.5 which has not been released yet. The beta is coming this week though. In this new version the number of ports will be reduced - in fact you'll only have to have one outbound port open (5655) in addition to port 443.
Hope that helps.