Choppy network connectivity / AirPlay problems on iPhones with mesh network - solved?

AirPlay is great when it works, being able to walk around the house while streaming, seamlessly switching between speakers or tracks even with your Apple Watch. Mesh networks are great when they work, providing full network connectivity all around the house even when it's large.

Unfortunately, in spite of quite high end hardware neither have worked for me for about a year. I have been getting choppy network reception when moving around the house, my HomePods have been all but bricked, and the Apple Watch has had no clue what was playing, let alone been able to control it. Coming from the mentioned network bliss situation and being a music lover, this has been quite a hard time for me.

I cannot really tell when it started, I read a lot of online articles on the subject and some attribute this problem to the specific iOS version 18.3.1. But around the same time, I got a new iPhone 16 Pro and a fancy new Netgear Orbi 770 mesh network, so it really could be all or either. A lot of people report iPhone / mesh network / streaming problems with any hardware or protocol

I could write a lot about my theories of why this works, but I'm not a technical expert so I'll cut to the chase: I solved the problem in 2 relatively simple steps - both my iPhone, my network, my Apple Watch and my HomePods now work as expected again. I want to share this with others who are as frustrated as I have been in case it works elsewhere: 

What you need to do is (especially bullet 2 requires a bit of technical finesse):

1. On the iPhone, open Settings -> Wifi -> Tap the (i) symbol to the right while using your mesh network. Tap Private Wi-Fi Address, then tap Off. Note the MAC / wifi address now shown - this is the actual, physical MAC of your phone.
2. Connect to the web interface (usually not possible in the app) of your router. Assign a fixed IP address to the MAC / wifi address of your phone you just noted (on my Orbi router, this is done in the Advanced/Setup/LAN section). I should mention that I have also had my HomePods on fixed IP addresses since before the problem started, but this changed nothing - the drastically changed behaviour came when I did a fixed IP for the phone.

This trick has the disadvantage that your phone is now easier to trace across networks, but unless you are a high risk hacking target, this is probably negligible (and it's what everyone did up to iOS 14).

If any of you have success with this procedure, let me know. If any of you technical wizards can explain exactly why this works, I'd also be interested. Especially if you're from Apple and actually could make this work out of the box without reducing the otherwise clever security on the iPhones...