Neptune is not that hard to find, in theory. Add light blinding pollution, a not so accurate polar alignment and some passing clouds, and it becomes a PITA.
The other thing is, that IF the object I photographed is indeed Neptune AND Triton, the moon is off compared to Stellarium. I intentionally photographed a reference star too, so I could put it on a map. However, the map itself is the DSS and some stars may have just moved away.
The gear: N 150/750, 2x Barlow and empty extension tubes, the ASI 224 MC camera, on the HEQ5 mount, in the city. 2018-09-11 22:26Z, ie 2018-09-12 1:26 local time.