The custumer has windows 7 64bits.
If he telnet from command prompt, the telnet is successfull.If he telnet from N2000 BMS client, the telnet fails.
N2000 BMS version is V200R012C05SPC136.
Change the OS type from 64bits to 32bits, the telnet is successfull.
We tried the with the same copy of N2000 BMS client on an other PC with the same configuration but different OS type 32bits. Telnet works normaly.