Hi Thomas,
*** In your post, you call out the "PDX-215c" model vs the?RLNK-215...
The PDX does not even have an ethernet port on it so I'm hoping that you miss-typed...
Assuming that you're controlling a controllable unit (RLNK models):
First, feel free to reach out to me directly if you want to chat about the specifics of your install...
Second, as mentioned I have used this module successfully with the RLNK-915R units, but have not used it with the?RLNK-215, though it should be the same.
I worked with MAP over the last couple years to sort out IP/Firmware issues with the initial (v01.02) and and interim (v01.10) versions. both had issues with DHCP and Static addressing schemes after a hard boot.
The current firmware version (v1.14.02 Release) has been solid. This would be the first place I would start, by verifying that you're running this version.
NOTE: the upgrade process will be messy regarding the IP address, so you will want to be on-site and be able to do IP scans to find the unit, etc...
HTH