Where? Can't get through either of the gates. Bugged?

In Homestead go Northwest to the fields and then West. Maybe you have to finish some quest before being able to go there, but I dont recall. Did you go back to Deadmans Gulch to get the troops there to town?

If you haven't already, you need to go back and let Ulgrim know you've secured the portal to Homestead before the gates will open. After that, you can then head out into the fields to purge the Dermapterans. You'll use the northwest gate as previously stated.

[edit] After thinking about this a bit later, you may first need to have spoken with Captain Somer and agreed to her quest before the northwest gate will open. You won't be able to get her quest until after Ulgrim has arrived at Homestead and has given you direction to do so.

Good luck.

I'll check about the troops at Deadman's Gulch as I don't remember. I haven't played all the way through GD for a while so have forgotten some things. I tend to go off exploring & then realise I have about a dozen quests to do lol