I have used Wemos, TP Link and Sonoff devices as smart switches. My experiences is as follows:
All of the Wemos I have replaced due to “state” issues. If they lose power and come back up they remain off.
I thought that the TP link would be my switch of choice but they have issues when power is lost. Sometimes when my mesh network goes down either from planned reset or power is lost in the house, some of the TP link devices come back up in an “orange state”, no internet connection. This is random. It always happens on different devices. All of my TP Link devices have seen this issue. I’m sure this is a firmware issue, but it is not resolved as of yet They can’t connect to internet. HA doesn’t see them and KASA doesn’t see them. They stay in this state until they are unplugged and replugged. Is this what you are seeing?
Sonoff devices. I have started using them flashed with Tasmota over they last several months. So far they have not had any connection issues (that I know of). They connect, reconnect, etc. Had to install and learn MQTT setup to use them in HA. Was not very difficult.
Are you able to see your devices with the Kasa application? If they are orange you may have the same issue that I an others in the TP Link forums have reported. If they are just losing connection I would look (as others have suggested) at your router. Signal strength maybe low, maybe interference from other routers, etc.