VeSync device suddenly result "unavailable"

Hello everyone.

I’m an absolute beginner with Home Assistant — I only discovered it yesterday.

Let me briefly describe my problem.

Yesterday, I installed HA on my small Linux server using Docker Compose.

My only goal was to manage a VeSync switch, model BSD60+.

First, I downloaded the app from the Play Store on my Android smartphone, created an account, and successfully added and tested the device.

Then, I added the same VeSync account in HA, which immediately recognized the device as well.

I tested the switch, and the lamp connected to it turned on and off successfully.

Today, I decided to continue setting up other devices, but when I went to test the VeSync switch again, it showed as “unavailable.”

I verified that it still worked in the Android app, that the Wi-Fi signal was fine, restarted the router, unplugged and plugged the switch, restarted HA, restarted the server, removed and re-added the VeSync account in HA — none of these actions changed anything.

Now, in fact, whenever I re-add the VeSync account, the device immediately appears as “unavailable.”

What could have happened?