Added two new meross MSS510 smart switches to my own home as I’m enjoying some simple home automation. Wiring was simple and the connection to my home automation system was seamless. Both switches joined my wifi without any issue — but afterwards I realized that I added them to the wrong SSID as I have two SSIDs. Simple enough, I’ll reset and re-add them to the proper SSID.

Reset both switches and added the first switch to the proper SSID. Easy. The second switch though, “could not connect to network”. Ugh. Weird, because they’re in them same junction box.

Reset the switch multiple times.

Restart my phone multiple times.

Turned the breaker off and on again. Nothing.

Checked the firewall DHCP leases. Both switches are shown based on their MAC addresses. Both switches are also on the proper SSID, but the switch that isn’t working has an IP address from the previous SSID, not the current SSID. Again, weird.

Reset the switch multiple times.

Restart my phone multiple times.

Turned the breaker off and on again. Nothing.

Wait a second. What’s the scope of the DHCP leases on the proper SSID? Yup, that’s the issue. When I previously defined my DHCP lease scope in the firewall, I had limited it to 20 IPs. This device, on that new SSID, would be device 21. Adjusted the scope to 25 devices, reset the switch and now we’re up and running. Switch worked fine all along. It was a firewall issue in the end.