@Mk9,
Unfortunately, this is a relatively common behavior for many network printers. Normally this is caused by your printer using a wireless connection to a specific mesh node, anything outside that node may be seen as outside a 'privacy mesh'. I would recommend looking at the documentation for your specific printer as there are often instructions or recommendations on how to configure the printer with a mesh network.

If your phone or PC is connected to the same node and the devices are not isolated from each other, you should be able to print. Otherwise, you may need to look at the resources that Brother offers.

Are your Decos in AP or Router Mode?

If, in AP Mode, there is an option to isolate AP traffic, and this would need to be disabled to print from the other nodes.