Technically no. I imagine you could use some silicone caulk where the shell meets the dome and the metal to waterproof it. There is moving parts in the relay that might be affected by heat or cold....

I have a similar setup at home. I have one HS110 that moves around the house. It does not matter what access point it connects to. It always comes online. If you are truly using the exact same SSID,...

@skaertus, I recently emailed TP-Link asking if the M5 still uses the mesh technology when the Deco's are configured as Access Points. They replied and said yes they do. I can't confirm though...