[Bug]: Bad upgrade process regarding proxy configurations going from global to per-account connection settings

[smcgu]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

Upgrading to Nextcloud desktop client 3.14.2 breaks account connections that use proxies. This is due to the switch from a "global" client network configuration to per-account connection settings. This has led to dozens of complaints and broken connections in my environment.

Steps to reproduce

1. Configure Desktop client proxy configuration
2. Add account
3. Upgrade to v3.14
4. Connection is now broken
5. Change account connection setting to use proxy -> works

Expected behavior

The upgrade process (or first client start after upgrade) should copy global network configuration information to all accounts when it detects the previous global setup (to the new per-account setup).

Which files are affected by this bug

All accounts are affected, all files

Operating system

Linux

Which version of the operating system you are running.

Ubuntu 22.04

Package

Distro package manager

Nextcloud Server version

N/A

Nextcloud Desktop Client version

3.14.2

Is this bug present after an update or on a fresh install?

Updated to a major version (ex. 3.3.6 to 3.4.0)

Are you using the Nextcloud Server Encryption module?

Encryption is Enabled

Are you using an external user-backend?

• Default internal user-backend
• LDAP/ Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

N/A

Additional info

I really like the new per-connection network connections but the current upgrade process (and path) is a breaking change.

[smcgu]

Alternatively and probably preferably, during the upgrade, the accounts should be configured to "Use global settings" instead of copying the global configuration to every account.

[smcgu]

This is related to #6890

[smcgu]

It is actually worse than expected. Switching an account to "Use global settings" does not persist across reboots. So, users have to reset the account configuration after every reboot.

1. Configure account to "Use global settings"
2. Reboot system
3. Connection is broken
4. Open account connection settings
5. Confirm that it is configured to "Use global settings"
6. Confirm that nextcloud.cfg contains the proxy configuration
7. Switch account to "No proxy" -> Connection restored
8. Switch account to "Use global settings" -> Connection restored, still

[smcgu]

I've opened a separate issue, #7438, for the broken reboot behavior.