Wow, it is so good. Thanks for your hard work.

two more things, here is the link to set the debug level and log file.
http://linksys.custhelp.com/cgi-bin/linksys.cfg/php/enduser/std_adp.php?p_faqid=19965
syslog program can be downloaded from Sipura or others. I did not try this yet.

How to set up stun: I would try setting NAT Mapping Enable YES, NAT Keep Alive Enable YES on the Line tab. On the SIP tab, I would try setting Substitute VIA Addr:YES. After trying those settings, I would retain them and try a STUN server by setting STUN enable Yes on the SIP tab and as a server using stun.voipdiscount.com.