Be grateful for any advice.

Over the last few months my wife who works from home has been complaining that Microsoft Teams will periodically freeze, then drop the connection at random times. I thought it was something to do with her work PC, but have finally worked out that it is actually the router dropping the WAN. Everything is over ethernet so no wifi involved. Spark Modem 3 system log reports that the WAN had dropped. This can occur once a day, several times a day, or sometimes we will get lucky and have 2 - 3 days with no dropping. I tried a 3rd party router (Unifi) and exactly the same thing is occurring. I have tried getting the router to connect over DHCP instead of PPPoE, and it still happens.

Unifi reports look like this

Internet connection WAN1 (Spark New Zealand) on port 5 is restored. Jun 24, 2025 at 16:17

Internet connection WAN1 (Spark New Zealand) on port 5 is experiencing packet loss. Jun 24, 2025 at 16:16

Spark reports look like this

Jun 25 11:09:12 Modem 3 user.info arc_link_state: WAN Link Down

Jun 25 11:09:12 Modem 3 daemon.info pppd[25740]: session_disconnect Send a PADT PPPoE:25740

Jun 25 11:09:12 Modem 3 daemon.info pppd[25740]: PPPoE main handle_events got_sig term

Jun 25 11:09:12 Modem 3 daemon.info pppd[25740]: PPPoE main handle_events got_sig usr1

Jun 25 11:09:12 Modem 3 daemon.info pppd[25740]: PPPoE client Exit. 25740

Jun 25 11:09:12 Modem 3 user.info arc_link_state: WAN Link Down Stage2

Jun 25 11:09:15 Modem 3 user.info arc_link_state: WAN Link Down

Spark help have asked me to plug the Chorus ONT (it is an original Model Type 100) into a different power outlet for a few days, as they wonder if it is a faulty power outlet to the ONT. But all my network switches, and the actual router are on the same outlet (4 outlet hard wired power board) and they don't fault.

Could this be a faulty ONT, or is there something else I haven't thought of here?

Thanks

Peter