A plugin for a cloud that no longer exists

Not in the HomeSeer store yet — running here daily, and heading for the store as a beta.

Belkin closed the Wemo cloud in January 2026 and retired the app with it. A great many perfectly good switches became, on paper, e-waste.

They didn't. Every Wemo speaks plain UPnP on the local network and always has — the cloud was a convenience layer, never a requirement. This plugin is that fact, turned into something HomeSeer can use.

Finding them, which is harder than it sounds

Discovery happens four ways, in tiers, because no single method is sufficient:

1. The neighbour table, filtered to Belkin MAC prefixes — a handful of targeted probes that find a device in under a second.
2. Remembered addresses from previous runs.
3. SSDP, when it works.
4. A full subnet probe on demand.

SSDP is listed third rather than first for two independent reasons. The replies arrive as inbound UDP that Windows Firewall drops by default for an unknown plugin executable — the same trap the Roku and Plex plugins hit — and long-running Wemos go SSDP-deaf entirely on their own. Either failure produces an empty list that looks exactly like a house with no Wemos in it.

Everything else is outbound TCP, which has neither problem.

Identity by serial, never address

DHCP moves and the firmware's wandering HTTP port are followed rather than fatal. The neighbour table answers where did this MAC go, so a device that changed lease is re-found by identity instead of mourned at its old address.

That technique came from the Hubspace plugin, where the cloud reports MAC addresses and never IPs. It has since been useful three times.

Provisioning: the part nothing else can do

The headline feature is a wizard that puts a factory-reset Wemo onto your wi-fi — using the setup service and Belkin's device-keyed password encryption.

No official tool can do this any more, because the official tool was the app, and the app is gone. Without it, a Wemo that has been reset is permanently a paperweight. With it, a box of them from a drawer becomes usable hardware again.

Things the hardware actually does

• The HTTP port wanders between 49152 and 49155 across reboots. Every failure re-probes and retries once.
• SetBinaryState answers with the literal string Error when the device is already in the state you asked for. Success, reported as failure.
• modelName is the generic "Socket" for the entire family. The recognisable name — Mini, Plug, Insight — hides in metadata field 5. The retail SKU appears nowhere at all.
• Energy figures come in milliwatt-minutes, a unit I had not met before and have not met since.
• The newer RTOS firmware removed the signal-strength call entirely. Only the older generation reports wi-fi signal — confirmed against the device's own service description rather than assumed.

The one I am proudest of finding

RTOS-generation Wemos send the Host header twice in their event notifications.

Windows' own HTTP stack rejects that unconditionally with a 400 that appears only in a log nobody thinks to look at. Which means HttpListener can never receive a Wemo push notification — not misconfigured, not fixable, simply never.

The listener is therefore a raw TCP socket with a deliberately tolerant parser, fed real captured notifications as test fixtures. There is a comment above it reading do not modernise this back, addressed to the version of me who finds it in two years and thinks it looks old-fashioned.