No one wants to hear that it's their wi-fi, but it's your wi-fi. Not all wi-fi is created equal. Not all rooms are created equal. Some have wires and stuff in the walls you don't know about. Not all devices respond to older modem and router protocols. Not all new devices appreciate old stuff. It's not a simple technology. Wi-fi is not like water coming out of a faucet.
Saying "something's wrong with Siri" on a command to set a timer is like saying "something's wrong with Google" on a search result. It's ludicrous. It's just bits of data from an enormous server farm. The problem isn't them. It's you.
I had many frustrating moments with my HomePods early on and the moment I got rid of my older router/repeater setup and went to a MESH network, what do you know, it's a Christmas miracle, I haven't had a single hiccup from Siri at all. Why? Because it's your wi-fi.