Internal extensions connect; external don't

Hi everyone.

I’m having problems installing an Asterisk 1.6 server with FreePBX 2.7. I’ve installed it in my office, and it works fine with X-Lite 3 and X-Lite 4. The problem is that the SIP clients doesn’t connect outside the office. We are using the same computers and clients inside and outside the office; they work inside, they doesn’t work outside.

My router is a Vigor2100. I have mapped the UDP ports 5060 and 5061 to the server, and I’ve openen the UDP ports 5004 - 5082, 4569, 2727 and 10000 - 20000. All the accounts have the NAT option enabled.

These are the contents of the sip_nat.conf file:

localnet=192.168.1.0/255.255.255.0
externhost=dipolowork.dynalias.net
externrefresh=10
fromdomain=dynalias.net
nat=yes
qualify=yes
canreinvite=no

When I try to register I always get the 408 error (request timeout). These are some of the logs that gives me the SIP client:

[10-10-05]13:41:47.317 | Info | RESIP:TRANSPORT | “Creating UDP transport host= port=24039 ipv4=1” |
[10-10-05]13:41:47.317 | Debug | RESIP:TRANSPORT | “Creating fd=1888 V4/UDP” |
[10-10-05]13:41:55.393 | Debug | RESIP:TRANSACTION | “Adding timer: Timer E1 tid=b0058d249d272401 ms=4000” |
[10-10-05]13:41:55.393 | Debug | RESIP:TRANSPORT | “Adding message to tx buffer to: [ V4 62.43.198.183:5060 UDP target domain=dipolowork.dynalias.net received on: Transport: [ V4 0.0.0.0:24039 UDP target domain=unspecified connectionId=0 ] connectionId=0 ]” |
[10-10-05]13:41:55.445 | Info | RESIP:TRANSPORT | "Connection reset " |

Any idea? Thanks in advance.