Hello, Aine here, one of the etke.cc developers.

The stats of the matrixrooms.info instance is what matrixrooms.info instance sees - it is not whole Matrix Federation. Here is the documentation in the MRS repo about that endpoint: https://github.com/etkecc/mrs/blob/main/docs/stats.md

Also, at the moment of writing, there are ~15k *federated* online servers visible by matrixrooms.info, and from them, ~4k servers publish their rooms directories over federation ("indexable").

You can read more about the MRS project (matrixrooms.info is just a demo instance) in the repo: https://github.com/etkecc/mrs/blob/main/README.md

Thanks for the reply.

This makes sense, but is there any reason MRS would see such a drastically smaller number compared to, what I assume to be, matrix.org instance numbers? My understanding based on the documentation provided is that MRS seeks federation-enabled, published rooms to index, and is the initiator of the connect. It doesn't expect other servers to reach out to it.

Or would this difference essentially be from servers that decided to disable indexing BUT still federate with matrix.org?

Yes, that's the difference. Loads of Matrix servers have nothing exposed to index, and steer clear of public rooms, and so wouldn't show up on MRS's stats.

Whereas I literally select count(*)'d from the destinations table on matrix.org, filtered on servers which had been federating in the last week(?) in order to get the specific stats above. (And then count(*) of all time for the 150K figure).

Thanks! This makes much more sense now!