Hello, friend!
It is confirmed that the HG8342R is a customized device model.
The home network management system has strict requirements for ONT management and registration. If the ONT is refreshed automatically, the ONT may fail to work properly.
Generally, ONT registration requires the upper-layer device to register device information or allow access and go online.
According to your description, the ONT fails to go online because the upper-layer device does not allow the ONT to go online or access the network.
You are advised to contact your local ISP or local engineers for a solution.
Thanks!