System:
two computer both of them win xp .
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network:
1-)192.168.1.140
2-)192.168.1.100
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1. firebird version 1.5.3.4870 db server
2. firebird version 1.5.3.4870 db server
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Both of two computer Listening port 3050 and active

Problem:
isql or other tools (ibexpert,ems,etc) not connect to each other

connection string for isql from 1. computer to 2.:

connect '192.168.1.100/3050:c:\firebird_data\test1.fdb'
user 'SYSDBA' password 'masterkey';

message:
Statement failed, SQLCODE = -902

Unable to complete network request to host "192.168.1.100".
-Failed to establish a connection.
-unknown Win32 error 10060
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Note:
2. c:\firebird_data (shared or unshared) not changed this problem