Without knowing exactly what ‘ solutions in the FAQ’ you’ve done, it’s really hard to give intelligent suggestions. Things I’d normally try are rebooting of the speakers, and the router, I’d also try updating them while wired to to the router. I’d also be looking for any potential VPNs, port blocking software, or virus protection apps, all of which might be restricting access to the Sonos update servers. 

But ultimately, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Thanks I'll give the diagnostics route a try. 

This is the support page for error code 1101: https://support.sonos.com/en-us/article/error-1101-when-updating-sonos

For reference I also have a bunch of modern speakers that work great on the newer app. It's just these 2 legacy speakers I'm struggling with. 

Is S1 still supported? I thought that might be my problem.

Yes, S1 still is supported.