The intake is 1/4" squares in steel. The exhaust is 1 1/2" pipe with a small piece of steel across the center of the opening. The could go in either way.
I've had the RV for 5 years and the nest must have been there when I bought it. I would know if there was wasps flying a few feet from the rv door.
I'm going to try replacing the electrode before the board. The troubleshooting guide says that the board senses the current draw to determine if it should go into lockout state. A new electrode is $7 on eBay so it's worth a shot. The nest was attached to the electrode.