pfSense

We have 4 installations of pfSense on KVM and configured a existing bind9 server with rfc2136 with your how-to (https://doc.pfsense.org/index.php/RFC2136_Dynamic_DNS).
On 2 installations everything works well - the WAN-Connection via PPPoE starts and the update is done.
On the other 2 installations no update is done - and on the bind9 Server with wireshark we don't even see a single packet coming.
We tried it with pfSense 2.15, 2.2 and 2.2.1, 2.1.5 updated to 2.2 and updated to 2.2.1. We tried to copy the VM from a working site and changed the settings. We tried also a 32bit 2.2 Version with fresh installation.
We tried also the TCP-switch, but nothing helped and we have either no or not actual log entries in System-General - e.g. we have this log:

Mar 9 10:40:39 GW syslogd: exiting on signal 15
Mar 9 10:40:39 GW check_reload_status: Syncing firewall
Mar 9 10:35:07 GW php-fpm³³⁴⁷⁸: /services_rfc2136_edit.php: phpDynDNS: updating cache file /conf/dyndns_wan_rfc2136_'THE-HOSTNAME'_IP-OF-BIND9.cache: 188.110.221.241
Mar 9 10:35:07 GW check_reload_status: Syncing firewall
Mar 9 10:33:29 GW check_reload_status: Syncing firewall
Mar 9 10:32:58 GW php-fpm³³⁴⁷⁸: /services_rfc2136_edit.php: phpDynDNS: updating cache file /conf/dyndns_wan_rfc2136_'THE-HOSTNAME'_IP-OF-BIND9.cache: 188.110.221.241
Mar 9 10:32:58 GW check_reload_status: Syncing firewall
Mar 9 10:30:10 GW php-fpm³³⁴⁷⁸: /services_rfc2136_edit.php: phpDynDNS: updating cache file /conf/dyndns_wan_rfc2136_'THE-HOSTNAME'_IP-OF-BIND9.cache: 188.110.221.241
Mar 9 10:30:10 GW check_reload_status: Syncing firewall
Mar 9 10:27:51 GW check_reload_status: Syncing firewall
Mar 9 10:27:43 GW php-fpm²⁶⁴⁹⁴: /services_rfc2136_edit.php: phpDynDNS: updating cache file /conf/dyndns_wan_rfc2136_'THE-HOSTNAME'_IP-OF-BIND9.cache: 188.110.221.241
Mar 9 10:27:43 GW check_reload_status: Syncing firewall
Mar 9 10:27:06 GW check_reload_status: Syncing firewall
Mar 9 10:26:08 GW php-fpm¹⁰⁶⁴⁸: /services_rfc2136_edit.php: phpDynDNS:updating cache file /conf/dyndns_wan_rfc2136_'THE-HOSTNAME'_IP-OF-BIND9.cache: 188.110.221.241
Mar 9 10:25:44 GW php-fpm²⁴²: /index.php: Successful login for user 'admin' from: 10.1.0.3
Mar 9 10:25:44 GW php-fpm²⁴²: /index.php: Successful login for user 'admin' from: 10.1.0.3

but the log was taken on 17. March - no single entry since a week, many reconnects and other ips since then and no update at all - at all means no update since installation.

We have logged on via ssh and send the nsupdate command per hand and it worked fine.
The .cache file is existing and contains the actual IP.

All machines have virtio network cards (Disable hardware checksum offload is set) and all other things are working well - many thanks for this great product.

What else could we try to provide you the right information to find (and eleminate) this bug....arrr..or our fault;-)