My laptop makes a loud noise when connecting to the internet, like a plane reving up for take-off.

Hello.

The most likely problem is the cooling fan. Could be clogged or faulty.

First, disconnect all cables. Be certain to dispel static electricity by touching metal. Remove the back cover to expose the fan. With a can of compressed air, blow the dust from in and around the fan. Replace the cover and cables and try again.

If still a problem, the fan would likely need to be replaced.

Hope this helps.