[asterisk-users] Loosing IAX connection between offices

[DM]

Setup:
Office A:
router: Linksys WRT54GS running SVEASOFT Alchemy-pre7a v3.37.6.8sv
Asterisk: v.1.2.4
static IP

Office B:
router: Linksys WRT54GL running Linksys firmware v4.30.2
Asterisk: v.1.2.7.1
dynamic IP (using dyndns name)

Office A is set up with refresh dns and cron job for iax2 reload every
5 minutes.  It rarely looses connection to Office B.

Surprisingly, Office B is the one loosing connection with Office A.
I'm surprised because Office A is the one with the static IP address.
When I do a IAX2 Show Peers, the connection will show as UNKNOWN or
UNAVAILABLE.  After loosing connection, the only way I can get it to
reestablish is to reboot the * box.  IAX2 reload doesn't solve it.  I
haven't been able to establish if it loosing the connection at a
specific duration.  Though, it seems to be random.

iax.conf of Office B:
[general]
bindport = 4569
bindaddr = 0.0.0.0
disallow=all
allow=ulaw
allow=alaw
allow=gsm
mailboxdetail=yes
notransfer=yes     ;(<- just added yesterday)

[officeb-user]
type=user
secret=<secret>
host=<static ip address>
context=from-internal

[officea]
username=officea-user
type=peer
secret=<secret>
qualify=4000
host=<static ip address>
context=from-internal

Any ideas on why Office B is loosing connection to Office A? or how to
re-establish connection without rebooting?