Recently I’m have the same few node entities go unavailable. Esphome shows its online, esphome logs show data from the entities. For example in HA a PIR motion sensor shows unavailable. If I look at the esphome node logs it shows the pir state changes in real time. It’s happening with dht sensors, pir, reed sensors and its happening on the same 3 nodes over and over. The only way I’m able to get it working is to delete the node and then re add it in esphome. It works for a while and then goes back unavailable.
I’m having this same problem with ESPhome and Tasmota devices. I can power my whole house down and they work normally for a few hours and one by one start to become unavailable. I cannot find the problem.
Mine randomly quit doing it now. I’m not sure wth was going on but it was only 3-4 nodes. Sometimes it would last an hour before going unavailable and other tines maybe a day. I havnt lost any for a few days now thankfully.