Newly repaired phone means re-trying all the apps. Fedilab and Tusky both fail to auth with toot.thoughtworks.com. Official android app works, but only by logging in twice.
On the positive side I've worked out how to have multiple accounts in the official app, and how to browse local timelines, so maybe it will suffice for now.
A Mastodon instance running on Thoughtworks infrastructure for its employees to interact with the Fediverse.