Some users report issues with pairing a eWeLink supported WiFi doorsensor. Mostly the device can not be found on the network. The device also seems to not support compatible pairing mode.
First some background on the issue
Whereas the ESP8266 and ESP8285 chipsets do support the WiFi protocols 802.11b, 802.11g and 802.11n the OPL1000 chipsets only supports 802.11b. All the protocols are protocols for the 2.4 GHz frequency band. The 802.11b WiFi protocol is one of the first (and thus oldest) WiFi protocols. This protocol is very outdated, supports only very slow datarates (which is fine for a WiFi doorsensor) and has security flaws.
Many modern routers and accesspoints do not have the 802.11b protocol enabled by default and some might even not support it anymore. In this case the app will only search on the WiFi protocols you are connected with (most likely 802.11g or 802.11n) and isn’t able to search at the 802.11b protocol since the router / accesspoints doesn’t offer the protocol at your wireless network unless you were able to enable it manually. All this will cause the discovery of the WiFi doorsensor in the eWeLink app to fail.
A solution is only possible when your router / accesspoint has the ability to turn on the 802.11b protocol manually and when you are willing to take the possible security risks which goes along with the 802.11b protocol. Please refer to the device manual of your router / accesspoint on how to enable the 802.11b protocol on your router / accesspoint.
If your router / accesspoint doesn’t allow you to enable the 802.11b protocol then the WiFi doorsensor can’t be used at your WiFi network.