The IP address is right, AMF870/15 is indeed connected on 2.4 GHz because that’s according to the specs, and there are no firewall rules blocking traffic to Homey.
I think the timeouts may be because I have a mesh network and both devices are connected to different mesh devices. This has given problems before with a printer which I then solved by moving the printer.
I don’t know when it happened, it may have been even before I sent the report, but the AMF870/15 is now connected and accessible.
I’m also going to connect Homey through the ethernet dongle, so timeouts should be minimal from then on.
Thanks again for giving this your attention.