Slow internet on desk, fine on mobile devices?

[SeverSman]

My iMac desktop and my work laptop have very slow internet. However, my iPhone and iPad are fine/normal. What could be the reason(s)?

[Jynxy]

Are they connecting via wirelss or ethernet ?

if wireless how old are the devices ? if they are older devices they wont have the latest wifi technology and will be slower.

When you say works fine on mobiles is this in the same location ?