WiFi Not Connecting

I have a new 645 Music with 3.7 firmware and it will not connect to my WiFi; I have seen some old posts about this but with no solutions or no solution that worked for me.

I have tried all sorts of things:

• Turned off Wireless Security (i.e. open network no password)
  
• Changed channels
  
• Set it up using Garmin Connect
  
• Set it up using the Watch its self
  
• Factory reset and removed device from Garmin Connect and done all the above again
  

And none of them will have it connect to my router I am sat next to. I have other 2.4ghz devices connected to that router fine.

I get a mixture of errors when trying to connect:

• "Connection Failed"
  
• "Connection Failed - Error Code 0700"
  
• "Transfer Failed"
  

I mostly get the first, a few times the second and once or twice the last, but never successful.

I enabled a hotspot on my mobile phone, and I got the same issues mostly except it did connect successfully once to it.

Anybody have any ideas?

(Incidentally maybe it thinks I am at the Earth's core and out of range of my router, being for every floor I ascend I descend 3).