Shriveled orchid with aerial roots, need help
 

Hello everyone, I am a newbie in all the senses of the word when it comes to orchids. I have had this orchid for four years now, it has never been repotted, which can see from this forum is highly recommended to do once in a while. I do water it once a week/two weeks, but I will be the first to admit I have not been the most diligent about it.

As can be seen, it has a lot of what I assume to be aerial roots. A lot of roots in the pot too. It looks very dry too and due to my lack of experience I do not know whether this means it has been overwatered or underwatered. My hunch is that it needs repotted and I need to adjust my care.

Any advice would be greatly appreciated.

Welcome to the Orchid Board!

That is likely a hybrid of Dendrobium nobile and related species. The time to repot is when it is making new growth. New growths form new roots, and need to be kept quite moist, else they wilt and don't grow to their potential. That is happening now.

The growths I see and aerial roots are coming from new plants forming on the upper parts of the stems. These extra plants are called keikis. I can't tell whether the base of the original stem is still alive.

I would very gently use a razor blade to separate the plantlets from the stem, then pot them up separately into a pot that just holds the roots mass. For potting medium you could use fine or medium orchid bark. Water the plant well during its growing season, so it never goes dry. During the winter it will be fine with watering every 2 weeks.

You can read more about this kind of plant here, at the now gone but archived version of the Yamamoto Dendrobiums US Web page:

Yamamoto Dendrobiums: Caring

Yamamoto Dendrobiums: Hints

It seems to be a Dendrobium nobile type. It needs lots of water in spring/summer.
Although it likes to be root bound, I would repot. Because it seems to be degraded, gently remove the medium from between the roots (with a gentle water jet, for ex) and cut (with a sterilised tool) the roots that are clearly mushy. Leave the others as they'll help to anchor the plant in the pot. I believe you can use the same pot, unless the root ball doesn't get smaller.
I would also spray water onto the aerial roots, for ex once or twice a day.
In winter, they don't like to be watered (only when you notice the pbulbs, aka "canes", are shrivelling).

Don't cut any pbulb because they bloom mainly from the older ones for several years in a row.

Give it bright indirect light all year.