is there support for Apple iwatch series 1

Yes, at an Apple Store or Authorized Service provider.

See here: watch Service Pricing - Apple Support

What kind of support?

Apple will still repair and service the watch for the out of warranty price if that's what you mean.

Why not? What happens when you try to connect it? If its issuing an error, tell us what it is.

Set up and pair Apple Watch with iPhone - Apple Support