I have a client in a managed office, and part of that service is the provision of internet, with static IPs for all desktops provided by the building, (I know it's a recipe to have all your data stolen, and you not even know!). They insist on saying that traffic is not managed, but we have different bandwidth available on different sockets.
Two desktops have blisteringly fast internet, and the rest have dodgy crappy internet access.
Is there anyway that I can prove that the traffic is being shaped, so that I can convince the powers that be to bring networking inhouse?
This could very well be a switch/cabling issue, or a configuration problem on the desktop themselves.
Anyway, a quick and easy test: take a laptop, plug it in socket A, download something big from a well-known high-bandwidth site (like Microsoft download center), measure time, move laptop to socket B, repeat, compare speeds.
Also, while you're at it, you can compare LAN speed (f.e. copying something to/from a file server): this will help you identify if the speed issue is related to LAN traffic also (which would definitely point in the direction of a switch/cabling issue), or only to Internet traffic (which would strongly support the traffic shaping theory).
It's not possible to tell if traffic shaping is taking place, but why would anyone bother doing that on part of a LAN?
I agree with @massimo's first sentence, it is more likely to be a cabling issue. The trouble is that moving a laptop about might not prove anything. What might be worthwhile is setting the NIC on the PC (laptop or otherwise) to fixed speed & duplex (if it is currently auto/auto) as that might match with the switch port setting whereas auto/auto will cause a duplex mismatch.
Sometimes Ethernet flow control may be a contributing factor. Please have a look at this article and see if it applies to your situation.