Photography] Just switched to Nikon and having trouble understanding my D810?

I just got a Nikon D810 and new Nikon 85mm f/1.8 G. I noticed that every time I use it to photography something very close, the focus isn't working. However, when I'm shooting far (1 meter away), it focuses perfectly.

Can anybody help me explain this?

Check the lens minimum focus distance, it won't focus closer than that.
If you need to focus closer than that, either using extension tube but you will loose long distance and infinity focus or using macro lens instead.

Sounds like the normal functioning of the lens. To use a camera close up, you will need a macro lens. The minimum focus for that lens is 0.8 meters.

Every lens has a minimum focusing distance. Your 85mm f1.8 can't focus any closer than 0.8 meters or 31.5 inches. If you need to get closer, I'd suggest getting the Tokina 100mm f2.8 macro lens. It's minimum focus distance is just under 12 inches at a 1:1 reproduction ratio. That means you'll fill more of the frame with your subject and have enough distance to light your subject with either flash or natural ambient light.

In addition what has been said: You can also use extension tubes, the better ones even support the autofocus function of your camera. As they have no lenses inside they won't reduce your lens' optical perfomance. An easy and cheap way into extreme close-ups.
Have a look here of what I'm talking

I'm curious. You bought a $2000 camera and wasn't aware of the concept of minimum lens focusing distance? You say you switched from another system. What camera did you have before the Nikon and how did you think the Nikon would make you a better photographer?

Read the manual for the lens. There you will find the lens' minimum focusing distance. According to Nikon, the minimum focusing distance for the 85mm f/1.8 G is 0.8 m/2.62 ft (from focal plane).

Your lens won't focus because it can't.

Do yourself a favor and read the manual of your lens, camera body and then buy a book on the fundamentals of photography.

If you need to focus closer than 0.8 m/2.62 ft (from focal plane), then you will need to buy a close-focusing lens filter, or an extension tube. Or, you will need to buy a different lens all together such as a macro lens.

This is such a basic, basic question that I have to seriously wonder why you purchased a D810 when you're clearly not ready for it.

All lenses have a minimum focusing distance. Find out what that is on your 85mm so you'll know how far you have to stay the next time you shoot.

If you really need to shoot something up close (very close) you need to get a macro lens (or micro as Nikon calls it).

Oh my dear gawd. Another Ferrari in the hands of someone who can barely drive.

… Sigh…

Life truly is not fair.