wcs2228
3
From your description, I assume that all the Sonoff devices work over 2.4GHz wifi (not Z-Wave or ZigBee that require a hub), that all the Sonoff devices show as actively connected on the CLIENTS page of the GL-AX1800, and that all the Sonoff devices have been paired successfully in the eWelink app.
Is your smartphone with the eWelink app also connected to the same 2.4GHz wifi network and showing as an actively connected on CLIENTS page of the router? If the smartphone is connected over cellular/LTE, then there may be an issue related to eWelink cloud communications that Sonoff Support should be able to troubleshoot.
There is no hard limit on the number of devices that can be connected on the 2.4GHz wifi network. You can also try resetting/rebooting one of the Sonoff devices and/or reinstalling the app.
I do not work for and I do not have formal association with GL.iNet.