OK, for anyone in this situation. This is what I had to do.
1. Get PUK1 and PUK2 from ATT for the sim.
2. Put sim in Peplink. Go into the details page for that sim and enter a SIM pin, in my case 1111. Then deactivated/reactivated. Then put in another sim pin, 2222, deactivate/reactivated that sim in dashboard. Then put in 3333 and deactivated, reactivated. I believe I had to do one more, 4444 for it to finally lock. If you click the ? next to the sim pin spot and then click "here" to manage sim (or somehting like that), it tells you how many tries you have left or if it's locked. This area will be used again later.
3. Put SIM back in Mobley and go to the admin page, and it will ask for PUK code and new pin. Enter PUK1 from step one and enter any pin. Say 1111. Then power off and pull sim from Mobley.
4. Put SIM back in Peplink and go back into the details for that sim. Click the ? to left of place you can enter a SIM pin, and then click on "here" in the message box that pops up. You will have a drop down menu/list where you can change disable SIM pin and it will ask for you pin, which we set to 1111 in step 3.
5. Back on the SIM detail page, make sure you remove the SIM pin you had entered to lock it in step 2 and save and apply. In the dashboard, you might need to drag the SIM down to disabled and back to enabled and then it should connect successfully.