Netgear LM1200 failover

It looks like the issue is with the LM1200 not properly failing over when both WAN sources are available. In scenario one, the failover works correctly when the cable modem is unplugged. However, in scenario two, with the cable modem plugged in, the LM1200 doesn’t switch to cellular as expected, possibly because it still sees the cable modem as "up" even if there’s no actual internet. When testing directly with your laptop (scenario three), it confirms the LM1200 is still passing through the upstream modem without checking true internet availability. One fix could be to ensure the Orbi router is detecting actual internet access before sticking to a WAN source, or manually disable the main WAN if it’s down. Unfortunately, the LM1200’s failover isn’t always smart enough to detect loss of internet, only physical disconnection. You might try setting the LM1200 to monitor a more reliable host or reduce the ping interval, but ultimately this sounds like a limitation in the LM1200's failover logic.