I spoke with @williangalvani about this, and was told that there were some recent mavlink2rest and water-linked API changes that are causing the issues here. The updated DVL extension should support the latest BlueOS and DVL firmware versions, as well as the api for older DVL firmware versions.
You can beta test it via the following instructions:
It’s a bit unclear, but it looks like the mavlink2rest API might have changed on the 1/March, in which case the latest version before that would be 1.0.0-beta13. That’s from before the first stable release, so is likely not advisable to go back to. If that is the case it at least makes some sense, because the idea was that once BlueOS was stable the core APIs should stop having breaking changes wherever possible.
I’m also unsure whether it’s possible to access older water-linked DVL firmwares, so if you’re already on the latest one then you may need to use the latest DVL extension, or wait until it’s released in stable form.