I have Apple TV in the living and upstairs in the spare room. For some reason, I can no longer stream to the upstairs one. Have a look at the attached image and see the image I am getting when I try to connect my phone to the two Apple TVs. One symbol is different to the other. Sufficed to say it won't connect to the upstairs one.

Does anybody know what is happening?

Click image to enlarge

have you tried renaming one to say apple tv2, it might be confusing the airplay as you have two basically identical devices on the network it might not know which to stream to.....

its done in the settings.  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
KIA E-Niro 4+
2021 Discovery 5 D300 MHEV commercial

I was trying to troubleshoot exactly the same thing at work a few weeks ago. (Hasn't solved it yet because you can't shut down the entire IT network.)

This was the recommended solution: on both the streaming device (iPod, iPhone) and the Apple TV, do a complete update and restore (not a reset). Also helps to unplug the modem they are both on and let everything reinitialise properly.

Let me know if that sorts it.

I run two apple TVs with no issues. one is Lounge apple tv and one is office apple tv. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
KIA E-Niro 4+
2021 Discovery 5 D300 MHEV commercial

My phone used to detect both with no problems. I did rename the upstairs one to see if it made any difference but it didn't. The upstairs one is jailbroken and it won't reset in the settings menu.