Hiding wireless router from the network.

There really isn't any way (certainly not easily) to distinguish a PC vs. router. They’d probably have to assume the latter based either on behavioral characteristics (e.g., unusually heavy traffic or sudden spikes in your usage patterns, assuming they’re even tracking that kind of information, seems unlikely) or packet inspection (which can be prevented by using a VPN). That’s because at the Ethernet level (which is all the information they have available), it all looks the same. There’s nothing in there that screams “I’m a PC” vs. “I’m a router”. In fact, it’s the use of standard interfaces and protocols that makes the network so flexible and work as well as it does. But that adds to the difficulty in attempting to distinguish the specific types of equipment actually using those standard interfaces and protocols.

Think of this way. Nothing says you couldn’t configure that very same PC as a router using ICS! In which case it’s both a PC and a router at the same time. Nothing happens at that point of transition that screams “now I’m a router” other than behavioral changes.

In short, the policy is almost impossible to enforce unless you do something obvious to make your router known. For example, use wireless; even if the SSID is disabled, it’s easily detecting w/ commonly available networking utilities. Or leave the administrative interface visible on the WAN (Internet) side. Or something far less technical; a house inspection, or someone just rats you out (the most likely reason, if it happens at all).