Couchbase Lite Enterprise 2.5.0 (for .NET) does not replicate with Sync Gateway

Yes. Again, the error is here:

Unexpected or unclean socket disconnect! (reason=Unknown error, code=10)

For some reason, the connection between the client and the SG is being interrupted. This is very unlikely to be an issue with either CBL or the SG. It is most likely to be something in your network. Perhaps something like this:

Can you get at logs for the SG? That might provide more insight.