#canon eos 80d

ive been trying to get into astrophotography and i just got my canon eos 80d but every time i try to shoot nebulae they come out totally overexposed... i know its prob a noob mistake but cant figure it out lol. ive been using the 18-55mm kit lens and trying to use manual mode but i must be doing something wrong... does anyone have any tips for a beginner like me??

So I've been trying to get some decent astrophotography shots with my Canon EOS 80D and SkyWatcher EQ5 mount, but I've been running into this weird issue where my stars are coming out all trailed and blurry. I've checked my polar alignment and it seems fine, but I'm starting to think it might be an autoguiding problem. I'm using a separate laptop to control the mount and camera, and I've got the autoguiding software set up to correct for any tracking errors. But for some reason, it's just not working like it should. Has anyone else out there had any experience with this kind of issue? I've tried adjusting the autoguiding settings and even switched to a different guide camera, but nothing seems to be working. I'm starting to get pretty frustrated with it, so any help or advice would be greatly appreciated.