What are the ways to detect a wifi router (on the provider's side)?

Question

Computer networks

So, there is a bad provider-monopolist (university, hostel - do not offer options to change the provider).
Internet is provided for each device separately by registering a mac address.
The provider forbids the use of routers without giving adequate arguments, but it is clear that the greed of the provider and the impudence of students explains everything.
Previously, the provider did this by setting ttl=1, that is, a message arrives at the router and dies. This affected programs such as Connectify, and even VirtualBox (networking did not work on guest OSes). It was treated by prohibiting TTL modification on the router.
Now a new method has appeared, as a result of which TTL is already 58. There is Internet on the router (addresses are assigned, sites are pinged), but on devices there is no access to the network. If you look at the packets in the web interface of the router, you can see that packets are coming from devices, but no responses from the provider are coming. What is most interesting, if any site is pinged from devices (for example, ping google.com), then the address is converted into an ip-address, and then the timeout is exceeded. And sometimes Skype starts working (which is very mysterious, because only Skype and only sometimes).
Therefore the questions are:

1. What are the ways to detect a router? (Question for reflection and satisfaction of interest)
   
2. How can I make the router completely invisible to the ISP?
   

ps If anything - ZyXEL Keenetic Extra router.

Answer 1

There is an elementary way to detect a router. =) The MAC address of the router that belongs to a specific manufacturer. It is enough to simply implement a check of poppies in the database and exclude devices from the pool of allowed ones. Plus, to ban the left poppies for a guarantee (if there are such in nature).

Answer 2

The MAC address of the router that belongs to a specific manufacturer.

I do not think that a person who knows how to disable TTL modification on a router does not know about the possibility of cloning a MAC address.

Answer 3

I am such a provider as you describe! You probably have a student dormitory in which in each room each student pays for a connected host, and you want four of you to sit on the same IP through a router and pay for one. As long as the provider's protection mechanism works, everything remains as it is. As soon as you learn how to use the router, the protection mechanism will be complicated. For example, I would add login and password authentication. The thirst for knowledge is commendable!

Answer 4

there is an option to compare packets at the IP level flying into the router and outgoing from it.
All the same, the TTL router can reduce, well, try to wave the poppy.
so there is an option that the provider uses the src-port, in Windows 7 and higher the range of dynamic ports is 49152 - 65535.
In general, you need to look at the contract, the provider provides the channel capacity, and then, in principle, he should not care how it is used ( except in cases of the Criminal Code of the Russian Federation)