The wireless routers that we provide our customers are part of a set and come with our service. The wireless routers have a function that allows the router to be used without any settings or changes (IPv4 over IPv6/IPoE).  The router model has been tested with our service, and if necessary, we will be able to provide support for the device. We are unable to say if other routers will work with our service since we cannot test the routers ourselves and confirm that they have the function (and even so, still work). Therefore, we respectfully ask our customers to use the router which we provide them. Should customers wish to use their own equipment, they are free to do so. However, we will not be able to provide official support for the usage of other equipment. 

It is possible to add a separate wireless router to the wireless router which we sent. You will need to place the new router in Access Point mode. Other setups are possible, as well. Please note, though, we are unable to provide support regarding this. We ask that you please contact the manufacturer of the wireless router that you intend to use to find out how to use the device in conjunction with our device and service. 
We thank you for your understanding regarding this.