Ok, I wondering if using two portals in the same polygon was illegal. Thank you for making that clear. I got the idea for the concave polygon from the flarge world file. This is the code in that file. This apparently seems to work in that map. I simply modified the xyz values to be positioned in my map. I assume from what you are telling me this was a poor example to follow.
<sector name="doorway">
<meshobj name="walls">
<plugin>thing</plugin>
<params>
<v x="-1" y="-1" z="5.6" />
<v x="-1" y="-1" z="6" />
<v x="-1" y="1" z="5.6" />
<v x="-1" y="1" z="6" />
<v x="0" y="-1" z="5.6" />
<v x="0" y="-1" z="6" />
<v x="0" y="1" z="5.6" />
<v x="0" y="1" z="6" />
<material>oldbrick</material>
<p name="north">
<v>3</v>
<v>7</v>
<v>5</v>
<v>1</v>
<portal>
<sector>large</sector>
</portal>
<texmap>
<matrix>
<m11>0.333333</m11>
<m12>0</m12>
<m13>0</m13>
<m21>0</m21>
<m22>-0.333333</m22>
<m23>0</m23>
<m31>0</m31>
<m32>0</m32>
<m33>0.333333</m33>
</matrix>
<v x="-1" y="1" z="6" />
</texmap>
</p>
<p name="east">
<v>7</v>
<v>6</v>
<v>4</v>
<v>5</v>
<texmap>
<matrix>
<m11>0</m11>
<m12>0</m12>
<m13>-0.333333</m13>
<m21>0</m21>
<m22>-0.333333</m22>
<m23>0</m23>
<m31>0.333333</m31>
<m32>0</m32>
<m33>0</m33>
</matrix>
<v x="0" y="1" z="6" />
</texmap>
</p>
<p name="south">
<v>6</v>
<v>2</v>
<v>0</v>
<v>4</v>
<portal>
<sector></sector>
</portal>
<texmap>
<matrix>
<m11>-0.333333</m11>
<m12>0</m12>
<m13>0</m13>
<m21>0</m21>
<m22>-0.333333</m22>
<m23>0</m23>
<m31>0</m31>
<m32>0</m32>
<m33>-0.333333</m33>
</matrix>
<v x="0" y="1" z="5.6" />
</texmap>
</p>
<p name="west">
<v>2</v>
<v>3</v>
<v>1</v>
<v>0</v>
<texmap>
<matrix>
<m11>0</m11>
<m12>0</m12>
<m13>0.333333</m13>
<m21>0</m21>
<m22>-0.333333</m22>
<m23>0</m23>
<m31>-0.333333</m31>
<m32>0</m32>
<m33>0</m33>
</matrix>
<v x="-1" y="1" z="5.6" />
</texmap>
</p>
<p name="up">
<v>2</v>
<v>6</v>
<v>7</v>
<v>3</v>
<texmap>
<matrix>
<m11>0.333333</m11>
<m12>0</m12>
<m13>0</m13>
<m21>0</m21>
<m22>0</m22>
<m23>0.333333</m23>
<m31>0</m31>
<m32>0.333333</m32>
<m33>0</m33>
</matrix>
<v x="-1" y="1" z="5.6" />
</texmap>
</p>
<p name="down">
<v>1</v>
<v>5</v>
<v>4</v>
<v>0</v>
<texmap>
<matrix>
<m11>0.333333</m11>
<m12>0</m12>
<m13>0</m13>
<m21>0</m21>
<m22>0</m22>
<m23>-0.333333</m23>
<m31>0</m31>
<m32>-0.333333</m32>
<m33>0</m33>
</matrix>
<v x="-1" y="-1" z="6" />
</texmap>
</p>
</params>
<zfill />
</meshobj>
</sector>