Indeed. Both NetworkManager.service and network.service do use all /etc/sysconfig/network-scripts/ifcfg-* files.
Renaming ifcfg-xx into off-ifcfg-xx would "hide" the file from them, but having backups elsewhere is better.
Is that traffic leaving with 192.168.102.205 or with 192.168.102.201 source address?
There are DHCP and firewall managed by some team? If they do decide to change what address they hand to you with DHCP, then they should update their firewall rules correspondingly. That is their job. You should not "hack around", but request service.
Good connectivity requires:
* Subnet, where local machines are
* Host address of this machine within the subnet
* Host address of the local machine that can forward traffic to other subnets (aka router, gateway)
* Address(es) of name resolver (DNS) servers
Judging by the earlier DHCP data the subnet is 192.168.102.0/24. In file that would be PREFIX=24, because one can calculate network and broadcast addresses from host address (192.168.102.201) and prefix (24).
I have no idea what the gateway in your subnet is.
The DHCP should have offered a DNS too. If your site has local DNS, then that is probably more efficient than Google's 8.8.8.8.
What does your current config give with: ip ro ?
The NetworkManager.servise shows "disabled", like it should not start at boot. However, you have it running.
I would make that more explicit with: sudo systemctl enable NetworkManager.service