I've followed the instructions to set up carefully but Deco M4 cannot allow 5 GHz only to work with the Main Network or the Guest Network setting. Anyone has the same problem?

My LAN settings:

- Main Network: 2.4 GHz only

- Guest Network: 5 Ghz only

- Device Priority: 0 devices

- IPv4: Dynamic IP

- IPv6: Disabled

- Most of other settings are default.

- I put my devices very close to Deco M4 for the good connection.

Test devices:

- iphone 7 

- Macbook Pro early 2011. v10.11.6

Test case:

1 - The Macbook Pro connected the LAN cable to Deco M4; the download and upload speed is 938Mbps and 889 Mbps

2 - iphone 7 connected to the wifi Main Network. Download and upload speed is 72Mbps and 95Mbps.

* Guest network with 5GHz is never to be disappeared whether before or after reboot.