Why are my cylinders giving me lines along their length? This has happened to me often. I don’t know what causes it or I’ve forgotten. When ever I create a glossy material on cylinders it gets stretched along the length in lines. I looks like there are 2 cylinders on top of each other. I am working on something and have abandoned it for the time being. I’ve seen this problem here before, but I can’t find it. Seems like the solution was adding geometry or something. These are not uv unwrapped cylinders.
Have you enabled smooth shading?
Add a couple of loopscuts towards the top and bottom endface and on the endfaces themselves?
Sorry if this is too basic, I’m kinda new to all this.
Mr. Newton! You’re no stranger to the forums so you should know that someone will always ask you for more information in the form of a blend file preferably, or at least a screenshot and that duty falls to me on this thread… 
I think I figured it out. I think I’ve asked this before actually. Seems that reflections don’t work unless you are in perspective view. That’s what was wrong. Thanks for the attempts at deciphering my issue though. Yeah been a while since I posted here and I ofc knew as soon as I did that I’d be asked for more info, but thought maybe it would be a very common thing that someone would know right off hand. So any future issues with crazy reflections and HDRI environment map not showing up correctly. Tell em to check that they are in perspective view first.