@Giles_H I think you need to set link backup, but need to enable load balance first, and then set up the failover. Actually the load balancing will be not active once you enable the link backup. Take...

@not-happy Do you mean you can not login the switch GUI if you enable the IPv6? Did you also set the IPv6 on the router?

@Antomicheal Hi, I have an answer from support team, and yes, I asked them several days ago, check this:

@Mayko7d Tried resetting the CPE, and you can also follow this document to do the recovery for testing.

@Rob5975 Hi, are these cameras tp-link devices either? Have you used Iperf3 to test the router's speed? If the lag issue only occurs on the cameras, maybe it is the trouble on the cams.

@phillip_mcmahon Did you try to forget the switch and EAPs and re-adopt them?