This network is really interesting with many repeaters and devices. It's set up for a farm with lots of equipment, which sometimes causes problems. After connecting devices, everything works smoothly, but linking to a repeater can take around 15 minutes to get an IP address. If anything disrupts the connection, you lose it again. Android phones adapt easily between sources, while Apple devices seem more sensitive. My router is a basic edge model, and all wired connections to repeaters function well, so the wireless issues are the main concern. Setting a reserved IP or static IP for a device usually helps, but sometimes it doesn't resolve the problem.
I'm no expert on Apple networking but my understanding is they need Bonjour support to be able to jump between different networks. The fact that all your devices work fine except the Apples would suggest its an issue with the Apple devices, not the network. Also remember there is a hard limit of 253 devices on any subnet (technically 254 but the gateway must always exist), this includes any repeaters and range extenders you may have.
Ensure every device gets a fixed IP address instead of a variable one. Set a static range for all routers that can support it. Then configure the router to reserve DHCP ranges outside this static allocation.
Yes, you can have static settings both in the router and on the device.