That seems like your tlp interface is not getting programmed right, or
is broken (design perhaps).
Can you restore/break again with in-tree tcpdump instead of
trafshow/pkgsrc libpcap?

with tcpdump -p, do you see incoming packets?
do outgoing packets make it out?

  tlp0 at pci0 dev 9 function 0: Lite-On 82C169 Ethernet, pass 2.0

I recall dimly that Lite-On is not a good chip; tlp(4) isn't wildly
enthusiastic about it, but doesn't mention your particular trouble.

-- 
        Greg Troxel <gdt@ir.bbn.com>