I know Surfers post was from a long time ago but I look to have the same issues.
Currently my M700s is not in the car but powered from a battery and being used inside. The wifi on 2.4Ghz lists all of the house Wifi 2.4Ghtz transmitters but none of the 5ghz. For it to use the phone Hotspot the phone has to be within 2 or 4 ft of the unit and even though the phone is dual 2.4/5Ghz it only connects on 2.4Ghz.
I turned on the M700S's own Hotspot set to 5Ghz and it shows up and the phone connects so it can transmit 5Ghz but does not seem to be able to receive 5Ghz or maybe it could if I set it right next to a router.
I thought it might help by fitting the 4G antenna but once fitted the results are the same. As I plan on using Bluetooth for Torque Pro it would be best if I could force 5Ghz Wifi but if it does not work that is scuppered and I will have to go for USB.
The black rubber coated 5Ghx antenna looks to be directly soldered to the board, maybe it could be replaced with an SMA type socket for a full 5G antenna to be screwed onto it like the 4G and the GPS.
See at 7.20 on this
That's not showing, search for '
EKIY T7 Tech Deep Dive & Tech Teardown / Overview for 200 Series Toyota Land Cruiser' on You Tube and go to 7.20.
Is there any hidden settings, I fixed my 5G on my Draytek router by changing the channels it transmits on and no more drops of service.
Update: I took a phone that can create hotspots on only 2.4Ghz or 5Ghz and set it to 5Ghz and put it under the unit next to the antenna and then did a wifi search on the Unit and the phone never appeared in the list. Odd when you can set the unit to create its own 5Ghz hotspot that works.