[Feature] Better (sync) failure messages

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

It'd be cool if immich gave more information upon failure.

An example:
<details>
<summary>
Immich on android fails to sync and gives up with a generic "Sync failed. Cannot process backup".<br>
In the logs there is no obvious stack trace. <br>
What is the issue?
</summary>
<br>
The server is ran behind a vpn and the user didn't enable the vpn.
Any error hinting to the fact that the connection is the thing that failed would give the user <i>something</i> to investigate in order to fix the issue instead of guessing.
</details>

Platform

• Server
• Web
• Mobile