Telnet to WL2k error

I am running Airmail on linux Mint for the first time
Experiencing the following error on telnet session :
Can anyone assist or advise .
Callsign :
ZS5BG
Password :
********
[WL2K-5.0-B2FWIHJM$]
;PQ: 40722410
CMS>
[AirMail-3.4.062-B2FHIM$]
;PR:
; WL2K de ZS5BG (KG50je)
FF
*** [2] Login failed - no response to challenge - Disconnecting (105.225.214.112)
2018/04/21 22:24:23 Telnet Port Disconnected

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