Could be a DNS issue. I believe the CCM best practice is to use the CCM IP Address instead of server name. Here is some good info for troubleshooting this issue;
Fixing Problems with IP Phone Services
If you confront an issue where you cannot access any IP phone services from your IP phone or, if you receive the error message Host not Found when you press the Services button on the IP phone, you might have problems with the Services URL. The Services URL might contain your server name or the wrong IP address. Therefore, your IP phones cannot resolve and access any services.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...