Hi  @itadmin2024 

Where is the mentioned switch plugged to? the LAN port of the CPE710 client?

If it works from the CPE LAN port, the switch may be defective, or there are some special settings.

BTW, Is it a TP-Link switch?

  @itadmin2024 Yes, our TP-Link switch is connected to CPE710 LAN port. 

Could be something on the switch, though. 

Hi  @itadmin2024 

What's the model number of the switch?

You can test like this: plug the switch directly into a router, and test the internet access.

Or you can refer to the following guide:

What can I do if my PC is not working when it’s connected to the Unmanaged Switch by cable?

  @Vincent-TP 

Switch model:
T1600G-28PS

Yeah, I performed the troubleshooting before posting.

Actually, we had an on-premise fiber breakage, thus I put this P2P as a temporary remedy.
No changes were made to the managed switches or other home routers. 

Strange because everything worked for a week and then this problem arose. 

Please refer to our network map attached herewith.