Hi, friend!
Can you provide the device version after the upgrade and screenshots of the error message?
Based on the error information you described: configuration method
You can refer to the article in the recommended answer:
Modify the configuration method.
gpon ont home-gateway config-method omci
Then, configure the WAN according to the subsequent steps
Because there are many commands, ensure that each command is correctly configured to ensure that services are available.
Thanks!