Thank you for your quick response.

I am new to Firebird and Jaybird. Reading the documentation you pointed to, it looks like both Firebird and Jaybird authenticate with Srp256 by default (and Legacy_Auth is not used by default). In my installation of both of those I accepted all defaults and did not make any changes to authentication methods - so I am a bit confused.

So, this morning I have just installed Firebird 4 Beta 1 on a Win 10 PC that has never had Firebird (or any other database) installed. (I'll refer to this PC as 'PC1' from now on.)

Before starting the Firebird server on PC1 for the first time I edited firebird.conf to ensure Srp256:

  AuthServer = Srp256

  AuthClient = Srp256, Srp, Win_Sspi

My understanding is this definitely means Srp256 is in use.

I can connect to the employee database on PC1 through iSQL on another PC (which I will refer to as 'PC2' from now on).

So, I presume the authentication done for iSQL on PC2 to connect to a database on PC1 is via Srp256 - that Srp256 proves it works, or does it?

When I try to connect to the employee database on PC1 via DBSchema (which uses Jaybird 4) on PC2 I get the "Error occurred during login, please check server firebird.log for details [SQLState:08006, ISC error code:335545106]" message, which, according to the documentaion you linked to, occurs if "no known plugins are specified".

As reported in my original post, firebird.log says "Authentication error No matching plugins on server" for the failed Jaybird connection attempt.