Channel width keeps reseting

This Hub 5 Wi-Fi issue was reported a few weeks back, a customer had the same problem
of manually selecting 160MHz bandwidth but finding it repeatedly reverting to 80MHz on the  5GHz band.

Hopefully you do not have VM Pods to compound the issue.

Do you have the VM Connect app installed on any of your mobiles ?

Do you have the VM Hub with Smart Wi-Fi / Wireless Channel Optimization enabled ?

If Yes to one or both, the VM Hub will re-apply the default VM profile for Wi-Fi connections,
( Shared SSID, Shared Credentials, Auto Channels ), 
we may be about to discover that profile also includes 5GHz at 80MHz channel bandwidth.

Try :
1) If present uninstall the VM Connect app from ALL mobiles & tablets,
2) From the Hub 5 menu: Disable Smart Wi-Fi & Apply Changes
3) Re-enable 160MHz channel bandwidth.
4) See if 160MHz is maintained.