supervisor: [homeassistant.components.hassio] Can't read Supervisor data:

Describe the issue you are experiencing

After a session of updating and adding new add-ons the Supervisor integration appears to have failed altogether or has become unusable. I am currently unable to access the Supervisor tab in the main UI, nor access any add-ons although it appears that previous installed, configured and started add-ons are still active in the background.

The response is intermittent in the sense that attempting to access to Supervisor tab will at times either: -and predominately display a blank screen; or -infrequently display a “Could not load the Supervisor panel!” banner and ‘Troubleshooting’ menu; and -on one occasion displayed the Supervisor panel ‘dashboard’, ‘add-ons’ and ‘system’ tabs but the content is unresponsive.

A small portion of the main Home Assistant log lists the following warning and error reports:

2021-11-13 19:14:37 WARNING (MainThread) [homeassistant.components.hassio] Can't read Supervisor data:
2021-11-13 19:15:27 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /core/stats request
2021-11-13 19:15:27 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /core/stats -
2021-11-13 19:15:27 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /supervisor/stats request
2021-11-13 19:15:27 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /supervisor/stats -
2021-11-13 19:17:36 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /backups/reload request
2021-11-13 19:17:36 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /backups/reload -
2021-11-13 19:19:11 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /addons/a0d7b954_vscode/install - 'AddonManager.install' blocked from execution, no host internet connection
2021-11-13 19:19:36 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /addons/a0d7b954_vscode/install - 'AddonManager.install' blocked from execution, no host internet connection
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_appdaemon/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_grocy/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/7be23ff5_dropbox_sync/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_grafana/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_ssh/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/core_samba/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_esphome/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_influxdb/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_nodered/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_chrony/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_nginxproxymanager/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/core_configurator/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_logviewer/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/a0d7b954_phpmyadmin/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/core_mariadb/stats request
2021-11-13 19:19:49 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /addons/core_mosquitto/stats request
2021-11-13 19:19:49 WARNING (MainThread) [homeassistant.components.hassio] Can't read Supervisor data:
2021-11-13 19:20:17 ERROR (MainThread) [homeassistant.components.hassio.http] Client timeout error on API request supervisor/logs
2021-11-13 19:20:17 ERROR (MainThread) [homeassistant.components.hassio.http] Client timeout error on API request supervisor/logs
2021-11-13 19:20:27 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /core/stats request
2021-11-13 19:20:27 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /core/stats -
2021-11-13 19:20:27 ERROR (MainThread) [homeassistant.components.hassio.handler] Timeout on /supervisor/stats request
2021-11-13 19:20:27 ERROR (MainThread) [homeassistant.components.hassio] Failed to to call /supervisor/stats - 

A fuller log can be found here: https://pastebin.com/5vN8PPeq

What is the used version of the Supervisor?

supervisor-2021.10.8

What type of installation are you running?

Home Assistant OS

Which operating system are you running on?

Home Assistant Operating System

What is the version of your installed operating system?

6.6

What version of Home Assistant Core is installed?

core-2021.11.3

Steps to reproduce the issue

1. Its permanent at the moment.
2. Followed the steps in the trouble shooting menu: Result of Home Assistant Observer Supervisor: Connected Supported: Unsupported Healthy: Unhealthy
3. Was forced to pull the power connection out to effect a reboot.
4. No change following reboot. …

Anything in the Supervisor logs that might be useful for us?

Am unable to access the Supervisor log. The error reported is:
Failed to get supervisor logs, 502: Bad Gateway

Additional information

No response