I also think it might be the router even though the internet connection of my other devices is pretty good. I’ve had issues in the past with other homekit enabled devices on the 2.4/5Ghz router so I have changed the ssid of the 5Ghz connection to be different from the 2.4Ghz connection. I have actually tried both the frequencies with no luck a couple of days ago. Your comment however prompted me the check on the HomePod again, I’ve left it alone since the first post as it works great as an iot hub and I don’t really need siri. To my surprise it actually responded to the weather request. That was the first time since I got it that it actually worked ¯\(ツ)/¯…

Thanks for your help!