With your very limited information of your implementation provided,  I would not comment too much, as changing these parameters in the wrong direction, or in the right direction but in the wrong way, may result in all enrolled devices getting out-of-control and might require recall  and factory-reset/device-reenrollment in the worst case.    My company got paid for these type of services to help customer avoid such problems, and we need to study the situation very carefully to evaluate the risks and sometimes need to consult with Soti experts for some tricky cases before proceeding.   This is important for production systems, especially those with massive number of devices/models enrolled.

I don't know if your system is on an open, semi-closed or fully closed network, nor the device platforms and enrollment mode of your enrolled devices and the MDM features your use-case requires.  However, in general, it is very unlikely that one should switch from using FQDN to using IP address in any modern MDM/EMM/UEM implementation managing latest or not-so-old devices, as many essential services and features are simply not possible/available without the implementation using FQDN and servers bind with strong SSL certificate for security reasons.