No players connecting to LMS

I've recently installed LMS on a new server.
I've powered down the old server.
I've set the new one up, and it's showing my mysqueezebox account details in the LMS settings.
In mysqueezebox, I can see all my players.

None of my players can connect to LMS. When I go to My Music, they try to connect to the old server. I can't find where to change this.
I tried a factory reset on one of the players, and it can't find anything. I can control this from mysqueeebox, but again can't get it to LMS.

It feels like there's a setting somewhere that I can't find, to either associate the LMS with mysqueezebox account, or to directly connect a player to the server with LMS. Does anybody know what this is?
From some guides, I'm supposed to be able to go to My Music on the player, then Switch Library, and then enter my server. But My Music just gives options for locally-hosted music to the player (which is not connected)

Server is a qnap TS-233. I installed LMS via the QLMS method https://www.qnapclub.eu/nl/qpkg/545 , which gave me 8.2.1.
I have a couple of SB Touches. Running 7.7.2-r9663. And a Radio.