have you rebooted your router?
you're using an airport express as your main router?
even though they have the apple name, they didn't have the best reputation when they came out, which was 6 years ago. the technology has improved quite a bit since then.
if you can update your router to something else, you might have better results. if you can't do that, try hardwiring your laptop.
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if it hasn't been too long, you might want to return the HomePod, and get something else
Without apple music, they aren't the most helpful, That's my situation and it's kinda annoying
"hey siri, turn on the kitchen lights", "There's nothing playing on this HomePod" "No sh*t, I never play music on you"
I hear "there's nothing playing" 3 or 4 times a week
my favorite though was a couple days ago, woke up early, still dark "hey siri, turn on the lights", silence, "MEOOOW" (as I step on the cat) "hey siri can you please turn on the lights" "ok, here you go" (the cat is fine)
Sonos will let you share a folder from your Mac, and use that as a music service.
Since it's using file sharing, instead of airplay, it will be much smoother.
If you do subscribe to another streaming service, chances are it's already on sonos. and you won't have to use airplay.
You do loose siri though, but have your choice of Alexa or google.
if you don't want voice control you can even save a few bucks (retail for the one is $199 with voice, $179 without)
IKEA also has sonos speakers for $99 (no voice), They work the same and sound good, but don't sound as great as the higher priced speakers.
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I do love apple gear, and have a ton, but you've mentioned what (in my opinion) are 2 items from towards the bottom of their list of products.
I keep the HomePod without Apple Music, because I have a lot of homekit, and it's nice to talk to siri for that.
also for sending messages and adding reminders.
for general knowledge questions, I have much better luck with Alexa or google.
Airplay is an OK solution, but not a great one. It depends on a solid network, and without that is prone to problems.
I use it from time to time, but would never depend on it as a long term solution.