nagiios core version 4

i have nagios core version 4.3  installeret på server ubuntu 16.04 . and nrpe version 3 og plugin 2.2.1 from client. on ununtu 16 and 14.
alle works . except for one ubuntu 16.04 i have error connection reset by peer )from nagios server)
from client when i say
./check_nrpe -H ipadress        then connection reset by peer
./check_nrpe -H       working  NRPE 3.2.1
./check_nrpe -H localhost    connect to address ::1 port 5666: Connection refused
NRPE v3.2.1

i have disabled = no on /etc/xie../nrpe
and  only_from       = client-ip  server-ip

from /usr/local/.../nrpe.cfg
allowed_host =,::1,client-ip,server-ip

like all other 16.04 and 14.04.
what is wrong?
Jasmin shahrzadAsked:
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nociSoftware EngineerCommented:
you also need ::1 in only_from   (you onlly allow, ::1 is ipv6 equivalent of that.
for the first check also the IP of the system you are checking from needs to be in the only_from & allowed_host.
(ie. if different from client-ip, server-ip),  also client-ip and server-ip need to be resolavable (/etc/resolv.conf or /etc/hsots).
(also when this server needs to bes tarted and the network is not up yet.

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