Hi,
I tried to make half bridge work on OPT1 (apparently Realtek 8139 recognised as rl1) with versions 1.2.1 and 1.2.3-RC1 using two different modems (Linksys AM200 and Zyxel P660R). I was not successful, even if everything worked perfectly with pfsense v1.2. Finally, I put one of the modems on router mode and pfsense in its DMZ and since then everything is working fine.
Cheers,