Need some help with portals

I'm trying to create a map in which the player keeps going around forever, unless they turn around and go back through a door that they just opened, which will take them somewhere else. The only issue is with the door. When the door closes, it's invisible, and it can't be activated. It's hard to explain through text, so I've uploaded the map.      

Any help would be much appreciated.

I think I found a solution. But first want to mention that in the map you uploaded, the door linedefs were pointing to Script 0 instead of 2 & 3, so I fixed that.

To correct the issue with the door blocking you, I widened the sectors between the line portals and door to 64 units (see image below). For line portals, there must be enough space on the other side of the linedef for an object to pass through the portal. Players are 32 units wide, but I did 64 just to be safe (the original width was 16, which is why the player couldn't fit). Now you can pass through the portal after the door is closed. But I'm not sure what's supposed to happen after that. I'll leave that up to you.

I attached the updated wad file to this post (limbo_edited.zip).

Also note that you will still hear the door close even though you can't see it because it physically exists close to the line portal.

Andarch

The DANDY Company

Check out my map that does similar things!

https://www.doomworld.com/idgames/levels/doom2/Ports/d-f/fuescher

Thanks so much for the help :)