Why does this token see the portal ? (Legacy dynamic lighting)

  Hey people, I'm wondering why the highlited token on this image sees the light emmited by the portal? In this situation, I gave 40ft. of darkvision to the token and the portal emits for 5 ft. The token's vision is not in range of the portal's light so I thought it wouldn't be showing. I did not put any walls as this is a forest with a clearing in the middle. So can anyone tell me, what am I missing in here?  Edit: Brand new to this, my players just gifted me the subscription so I'm trying to setup things properly for them

Does the portal token "have sight", and does the "controlled by" property of the portal token include the character token's player? If so, that might be it, as  players can see through whatever tokens they control. 

Sorry, I just re-read your post. The darkvision token should be able to see the portal if nothing is blocking its sight. Just like you would see a glowing portal 100ft away from you even in total darkness. There would need to be some kind of barrier on the dynamic lighting layer to actually block the token's field of view. You could put simple blocking lines/polygons at the base of each tree to simulate tree trunks blocking LoS, for example

Ohhh yeah I get it. I think i was going for too much pure numbers thing... I'll try a different approach, thanks !