Sometimes, actually fairly often, i experience that my lights are not as responsive as they should be. I have a combination of Shelly’s, IKEA bulbs, normal Philips bulbs and some Aqara sensors.
I’m not on my Hass instance every day. Far from it. Every time it happens, the first thing i do is log into my instance, open Z2M and then it works. It’s like it goes into some kind of sleeping mode if nothing happens for X hours.
If the computer where you are running Home Assistant and Zigbee2MQTT is going to sleep, then yes that is going to cause you problems. That’s not a Zigbee2MQTT issue.
You should be able launch a browser on another computer on your network and navigate to the Zigbee2MQTT web front end page IP address and port. If you end up with a unable to connect in the browser via this method, then yes suspecting that your ‘server’ computer is going to sleep might be the problem.
look at the zigbee2mqtt log file. And share relevant parts here are part of your request for help.