VXDIAG VCX FD Cannot Connect via DoNET Solution

One of our customers was trying to connect VXDIAG VCX FD VCI via DoNET (5GHz) but failed. Photo attached:

It should be noted that VXDIAG works with 2.4GHz DoNET remote connections and does not appear to recognize 5 GHz connections.

He changed to another phone (2.4GHz) and it worked fine.