Facing issues with Ports and HTTP.

Hello buddies, from somedays I am facing connection was reset by peer issue in my dedicated server. The Following are installed in my server : CPanel CloudLinux LiteSpeed ConfigServer Firewall Imunify360 I asked my friend he said that someone doing Ddos on your server. sir I checked my IP on check-host.net, and I patched a issue that when UDP Ports showing connection refused then HTTP shows OK but when UDP Ports shows Opened or Filtered then HTTP shows Connection was reset by peer. If any expert have solution please tell I will be thankful to everyone.