Frequent unregistering of Gigaset N510 IP Pro Dect Base

Equipment:
Gigaset N510 IP Pro Dect Base station plugged into Netgear gigabit poe switch
FreePBX 2.10.1.19 running on a physical Asus EeeBox
Asterisk 1.8.3 on CentOS 5.5
CSF firewall on box as well as hardware firewall only allowing IAX trunk from providers IP.
5 x Working Polycom IP321
1 x working Linksys SPA with analogue trunk and analogue extension for a regular DECT base.

Symptoms:
IP Dect account registers but unregisters often sometimes every couple of minutes typically 4, sometimes will go longer. If I’m using it to make a call then the call will drop. Handset displays connection to IP provider failed.

Troubleshooting so far:
enable SIP debug which shows typically:

[2015-11-09 19:22:53] DEBUG[5347] acl.c: For destination ‘192.168.101.121’, our source address is ‘192.168.101.250’.
[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Setting SIP_TRANSPORT_UDP with address 192.168.101.250:5060
[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Allocating new SIP dialog for [email protected]_168_101_121 - REGISTER (No RTP)
[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Trying to put ‘SIP/2.0 100’ onto UDP socket destined for 192.168.101.121:5292
[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Trying to put ‘SIP/2.0 401’ onto UDP socket destined for 192.168.101.121:5292
[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Trying to put ‘SIP/2.0 100’ onto UDP socket destined for 192.168.101.121:5292
[2015-11-09 19:22:53] DEBUG[5347] db.c: Unable to find key ‘120’ in family ‘SIP/PeerMethods’
[2015-11-09 19:22:53] VERBOSE[5347] chan_sip.c: – Unregistered SIP ‘120’
[2015-11-09 19:22:53] DEBUG[5402] manager.c: Examining event:
Event: PeerStatus
Privilege: system,all
ChannelType: SIP
Peer: SIP/120
PeerStatus: Unregistered

[2015-11-09 19:22:53] DEBUG[5347] chan_sip.c: Trying to put ‘SIP/2.0 200’ onto UDP socket destined for 192.168.101.121:5292
[2015-11-09 19:22:53] DEBUG[5318] chan_sip.c: Checking device state for peer 120
[2015-11-09 19:22:53] DEBUG[5318] devicestate.c: Changing state for SIP/120 - state 5 (Unavailable)
[2015-11-09 19:22:53] DEBUG[5318] devicestate.c: device ‘SIP/120’ state ‘5’
[2015-11-09 19:22:53] DEBUG[5319] devicestate.c: Checking if I can find provider for “Custom” - number: DND120
[2015-11-09 19:22:53] DEBUG[5319] db.c: Unable to find key ‘DND120’ in family ‘CustomDevstate’
[2015-11-09 19:22:53] DEBUG[5319] app_queue.c: Extension ‘[email protected]’ changed to state ‘5’ (Unavailable) but we don’t care because they’re not a member of any queue.
[2015-11-09 19:22:53] DEBUG[5400] app_queue.c: Device ‘SIP/120’ changed to state ‘5’ (Unavailable) but we don’t care because they’re not a member of any queue.
[2015-11-09 19:22:53] DEBUG[5402] manager.c: Examining event:
Event: ExtensionStatus
Privilege: call,all
Exten: 120
Context: ext-local
Hint: SIP/120&Custom:DND120
Status: 4

created a new extension with default settings
tried different ports on poe switch
updated firmware on IP dect base v42.210
turned off fail2ban
then I turned csf off and iptables

still unregistering…

I’ve just got a new panasonic kgp600 dect = working fine with same setup.