They do. If you are located anywhere in the EU that is illegal as EU regulation 2015/2120 applies to them. More specifically, article 3 which explicitly says:Some ISP are also strict with their equipments on Modem+Router.
There are times you need to do Mac Clone to get IP address on your personal router in case users ditch the provided one by ISP.
1. End-users shall have the right to access and distribute information and content, use and provide applications and services, and use terminal equipment of their choice, irrespective of the end-user’s or provider’s location or the location, origin or destination of the information, content, application or service, via their internet access service.
2. Agreements between providers of internet access services and end-users on commercial and technical conditions and the characteristics of internet access services such as price, data volumes or speed, and any commercial practices conducted by providers of internet access services, shall not limit the exercise of the rights of end-users laid down in paragraph 1.
3. Providers of internet access services shall treat all traffic equally, when providing internet access services, without discrimination, restriction or interference, and irrespective of the sender and receiver, the content accessed or distributed, the applications or services used or provided, or the terminal equipment used.
The only catch? Your national regulator decides what the best model is; whether allowing you to completely ditch ISP router or just allowing you bridge mode. Croatian regulator HAKOM chose the second option. Despite that, there are instructions on local forums how to ditch the ISP equipment completely with disclaimer you're responsible for the consequences if ISP realizes you stopped using their equipment on your own.



