Local multiplayer does not work

We have a mixture of devices, a Lenovo android tab, two PC's running windows 10 and a couple of Nintendo Switches.

If we create a world on any of these devices and other devices are on the same WiFi network, running minecraft, and logged into their microsoft accounts, the local multiplayer world will not normally appear.

Occasionally, after several minutes, the game might appear on other devices, but not always. If it does, it will either time out trying to connect, or the connection will fail a few minutes after joining the game.

Using the find other players option from another device will correctly report that the player is playing minecraft on their device, but that game will not be visible to join.

– YES, I have checked that the multiplayer options are set correctly in the device running the game!

--YES, we are all running the latest version of Minecraft on each device.

--YES, the windows PC's are running Bedrock edition.

--We have tried hosting games on every device and then tried to join from different devices, nothing like this works

--We have tried using different WiFi networks. This doesn't help either.

I would estimate that 90% of the time the game will not appear as a local multiplayer at all, and of the 10% when it does, half of those times it will time out when attempting to join.