Hi,
inReach Messenger manual page 3 quote "Iridium Satellite Network Your device requires a clear view of the sky to transmit messages and track points over the Iridium satellite network. Without a clear view of the sky, your device attempts to send the information until it acquires satellite signals. TIP: For the best connection with satellites, the top of the device should be oriented toward the sky."
Hereby:
-a set of attachment elements: https://www.tasmaniantiger.info/en/product/tt-cable-manager-set/
-an adapter for the shoulder strap of the backpack: https://www.tasmaniantiger.info/en/product/tt-harness-molle-adapter/
I'm not affiliated to tasmanian tiger gear.
Kind regards,