Sonoff custom integration - Won't work on local network?

Hi guys, quick question here.

I’m using custom Sonoff integration (GitHub - AlexxIT/SonoffLAN: Control Sonoff Devices with eWeLink (original) firmware over LAN and/or Cloud from Home Assistant) for a good while now, over a year, and it seems that in the last couple of months it doesn’t want to work (properly) over local network. Has anybody else had similar problem or noticed this behaviour?

A bit more meat:
I don’t have HACS, it’s a manual installation. I have a Micro USB switch, which was btw blocked in router from accessing the net. Everything was working fine, until I recently started noticing that after a HA restart Sonoff Micro device would go to Unavailable. (Same thing if the integration was reloaded). Also it wouldn’t change state in HA (automation turns it on and off, but it would constantly be in On state, although device connected to it would turn on and off so I knew commands would go through). So device is apparently OK, but HA integration seems to somehow malfunction? I’ve tried “reinstalling” it, or removing it and adding it back again, but with no luck. If I unplug the device and replug it back, then it comes back from Unavailable, but doesn’t change state until it dies again.
Only seem to work properly once I remove the internet access block in the router.

I have RasPi 4 with HA OS. My HA was version 2013.12 until yesterday when I updated to 2024.4. SonoffLAN was something older (maybe 3.4.0 ?), yesterday updated to 3.6.0. I have eWe account and the device is added there. (don’t know how to add device without adding it to eWe app)
Behaviour is exactly the same.

Any suggestions or ideas?