Since today one of my extension goes in 1 minute directly to UNREACHABLE
[2018-02-03 11:14:03] VERBOSE[9247] chan_sip.c: Registered SIP '200' at 192.168.0.21:5060
[2018-02-03 11:14:03] NOTICE[9247] chan_sip.c: Peer '200' is now Reachable. (3ms / 2000ms)
[2018-02-03 11:15:07] NOTICE[9247] chan_sip.c: Peer '200' is now UNREACHABLE! Last qualify: 3
The other extension don’t have this problem, any suggestions?