Try now if it works.
My IP blacklisted?
From one host
root@vz45447:~# telnet stratum.nicehash.com 3336
Trying 159.8.2.66...
Connected to stratum.nicehash.com.
Escape character is '^]'.
^]
telnet> quit
Connection closed.
from other
root@bamt-miner:~# telnet stratum.nicehash.com 3336
Trying 159.8.2.66...
telnet: Unable to connect to remote host: Connection refused
banned host 213.87.122.0 , but can moved over 213.87.0.0/16 network.
Using telnet will only help you get on banlist sooner. Telnet doesn't act as miner, ergo our system will sooner or later blacklist as an attempt of attack.