I have two ISP's, T-Mobile 5G and Frontier DSL into the ER605 ,the ER605's port LAN4, into an SG2210P and then 2 EAP110, 2 EAP 650. in the OC200, it shows firmware is up to date on all devices.

The OC200 was the first device configured for the site, then the switch, then the router.. then the EAP's

For load balancing,  that may be a moot point as the T-mobile line is 0ver 10x faster that the DSL, however upon unplugging or disabling the cable/interface on WAN1 (tmobile) there is very limited but unusable fail-over to the Frontier DSL. What I mean by that is the ER605 manages to top out at 0.5mb/sec, when I plug my laptop into the same DSL router, I get the advertised 20mb/sec down and 3 up., other than when I test, the ER605 is the only device plugged into the DSL router and the ER605 is the only client on that router, as WiFi has been disabled on the Frontier router. physically  both devices are in the same wall cabinet, well ventilated of course.

I've tried multiple settings on the load balance ratio and failover only vs load balance, swapping WAN1 and WAN2 ports etc but none of the configuration changes have made a difference. I've hard (factory) reset the router a couple of times  and adopted from scratch. still no fail-over.

I bought the ER605 to replace an Edgepoint EP-R6 that router was working/failing over with no issues, I only replaced  to get the unified omada reporting.which does not seem to be working as statistics show zero clients , that's router statistics via the OC200 reporting, the lan clients are all showing up on the OC200.The router throughput statiscts shown on the OC200 look suspect as they are always <1% and we have multiple camera systems to the outside world and users who are large consumers of 4k streaming video. I've tested by running multiple concurrent downloads of various Linux distributions at >3mb/sec per stream, yet the ISP load on OC200 shows <1% utilization. On the OC200, Internet capacity is configured as WAN1 (tmo) 50 up and 80 down/WAN2 (DSL) 3 up and 20 down.