I cannot duplicate your problem, or perhaps I am not understanding your situation. My C-more does not update its IP from ".29" to ".029" upon power cycles. Actually my C-more suppresses leading zeros. If I enter ".029", my C-more suppresses the zero and displays ".29". (perhaps a leading-zero-suppress setting)

BUT, this ".029" should not be the problem that the C-more cannot read/ write data to the PLC ECOM.

I can assign any IP (within range) to the C-more, and the C-more will still read/ write data to the PLC (thru the ECOM) as long as the PLC ECOM IP address is entered correctly in Setup > Panel Manager, and is on the same subnet as the C-more IP in Setup > Panel Network.

Double check that your PLC ECOM IP and C-more IP are on the same subnet, that your "DEVxxx" is pointing to the PLC IP in C-more Panel Manager, that your C-more screen objects are using the "DEVxxx" that connects to your PLC, and that there are no C-more screen objects trying to connect to obsolete Devices.

(I'm using D2-260 with H2-ECOM, and setting H2-ECOM IP using NetEdit3)