Unable to connect to homeserver, retrying... - Lost access to homeserver on mobile, web, and desktop apps after logout

[johndball]

Steps to reproduce

1. This behavior has started recently after a user logs out of a client on a self-run homeserver. This issue is on the Element Windows desktop app 1.10.13 and app.element.io on the web.
2. I logged out and am unable to log back in. On my mobile device, I am prompted with a "verify session" prompt, but the client never loads on desktop or web.
3. I opened developer view on the web and I can see "Number of consecutive failed sync requests: 36" and other issues related to syncing.
4. UPDATE - After posting this I tried clearing cache on my mobile Element and second desktop. I've now lost access to my homserver on mobile as well. iOS 15.x. I've effectively lost all front-end/user access to both homeservers now and can no longer interact with any users on either server at this point.

This behavior mimics the issue on #12694 but I did not want to revive a 2 year old thread.

Outcome

What did you expect?

A log out and log back in should work after successful authentication.

What happened instead?

Client just spins and no login occurs.

Operating system

Windows

Application version

1. 10.13

How did you install the app?

https://element.io/get-started#download

Homeserver

Self-hosted, both on Ubuntu 20.04 LTS, Apache2, Matrix 1.59.1

Will you send logs?

Yes

[johndball]

After trying multiple "things", I ended up rolling back to Matrix Synapse 1.57.0 from 1.59.1 and my clients (web, mobile, desktop) instantly signed in. Not entirely sure this is an Element issue...

[t3chguy]

Closing in favour of matrix-org/synapse#12820

I can see in developer tools that there is a never ending /sync job. This is the issue I opened in Element