The model 3 is extremely hard to program for a community gate. I tried all of the methods above for both of my 2 model 3’s.
Here is the best method after repeated trial and error hands down, and fresh batteries are recommended:
1) Park close to gate.
2) Open front hood trunk.
3) Initiate learning sequence
4) Point remote from inside of front hood trunk towards the middle front where the latch from the hood fits, NOT from the outside of the car towards the nose, rather from inside the trunk pointing towards the nose, specifically aiming at where the latch hole is.
5) As pointed out above, multiple 2 second bursts work the best until the front lights flash.
After I figured it out for my Model 3, I was able to rapidly program the SO’s Model 3 and end a long history of nagging.
Just my tried and true $0.02.
Enjoy!