>>>Can you connect locally by using TCP/IP(i.e.: using localhost or the
>>> server's own IP)?
>
> Just my 2c. We have also experienced this on a few PC's.
>
> A connection string of:
>
> localhost:c:\MyFolder\MyData.fdb
>
> gives the connection rejected error.
>
> Changing to:
>
> c:\MyFolder\MyData.fdb
>
> resolves the problem.
>

I believe this switches the connection protocol to XNET and not TCP/IP so
I don't think it would fix the issue should I need to connect from another
machine.

Here is an excerpt of the firebird log file when attempting a connection
with ibmanager:

XS001 (Client) Mon Aug 07 15:58:12 2017
INET/inet_error: read errno = 10054

XS001 Mon Aug 07 15:58:12 2017
inet server err: setting KEEPALIVE socket option

XS001 Mon Aug 07 15:58:12 2017
inet server err: setting NODELAY socket option

XS001 Mon Aug 07 15:58:12 2017
INET/select_wait: found "not a socket" socket : 236

XS001 Mon Aug 07 15:58:12 2017
INET/inet_error: select in packet_receive errno = 10038

XS001 Mon Aug 07 15:58:12 2017
Unable to complete network request to host "XS001".
Error reading data from the connection.

This is the error returned:

Connection rejected by remote interface.
SQL code: -923
IB error #: 335544421


Thanks!