In my mind, if the server is in a datacenter, you are using a hosted server. Who physically maintains the server at the datacenter? Is it a VPN? I'm guessing you are paying someone to use the server - that would be your host. Can a panel -like cPanel - be added to make access easier?
Are any emails able to be sent from the site?
Are email sent thru the site getting to the admin email? New PIREP submitted, new pilot registration, new Contact Us submittal?