Where can I find a technician to install and configure a genieacs server for me? Im an ISP

I already have faced some CPEs bugs on the implementation of TR-069. The most recent one was with ZTE F670L and F680, the problem was when I try to set: InternetGatewayDevice.ManagementServer.PeriodicInformTime
In response, I get an error of cwmp.9003 Invalid arguments.

I think that is a facturer problem because the actual value is equal to InternetGatewayDevice.ManagementServer.PeriodicInformTime -62135596800000.
I only can set with success the same value. If I change to something else that is not equal to -62135596800000 I get an cwmp.9003 Invalid arguments.

With your vaste experience with TR-069. Have you faced something like this?