Homepod setup failed - errors 6753 and 71160

My homepods had errors signing into my icloud account, and per a suggestion on this forum I removed them from my home app and factory reset them. They now cannot be re-added. Setup fails every time. Things I have tried:

• Restarting my router
• Signing out and signing in again on my phone
• Ensuring the homepods are fully removed from both my icloud account and my home app.
• Plugging in the homepods directly into my computer and doing a firmware update
• Doing factory resets on the homepods

So far everything has failed with them - this is happening with two homepods that were previously in a stereo pair. I have other homepods on my network that are working fine.

Any ideas how to get them to set up again?