When I logged into deployment-cache-mobile04 and ran puppet earlier, I found that role::cache::mobile had been completely removed in https://gerrit.wikimedia.org/r/#/c/268229/ (meaning puppet on the instance was completely broken - the other deployment-prep cache boxes also had puppet broken due to https://phabricator.wikimedia.org/T129270).
I checked LDAP and didn't find any other labs instances using the role (ideally people would check this before merging puppet patches that remove roles...)
So I've moved all of the m.*.beta.wmflabs.org domains/subdomains over to deployment-cache-text04. I've left the public IP pointing to the old mobile instance for now, but in the absence of any issues, I plan to release the IP and delete the instance soon.

Please let me know if you see any problems.