I've got a Netgear CM400 cable modem and am wondering if I can use it in the UK or if I should just sell it off now.

I have looked at the website but it is entirely US-centric. Hoping someone else may know about compatibility.


You may as well sell it off. The CM400 is a DOCSIS cable modem. With very few exceptions, UK cable ISPs require subscribers to use a modem or router supplied by the ISP. Most UK ISPs will refuse to activate a 3rd party device. This is unlike in the USA, where Netgear advertise the CM400 with the slogan "Lose the Lease. Keep the Speed.". In the UK the 'lease' of the modem or router (and these days it's almost invariably a rebadged cable modem and wi-fi + ethernet router in the same casing, locked to the ISP's system) is absorbed or hidden in the monthly charges. There has been some movement within the EU (which the UK is currently planning on leaving) towards more freedom to choose your own 'terminal equipment', but this is in the early stages. You could bring it over, I suppose, and when you are settled at your UK address, find out what cable suppliers serve your area, and ask them if they will activate your modem. Be prepared for them to say 'no', in which case you have a useless modem and you are 3,000 miles away from anyone who might want to buy it. With most ISPs, when the cable company's install technician comes to call, he or she will bring a router, and want to connect it up and activate it anyhow. Some ISPs (notably Virginmedia) will allow you to set their supplied router into 'modem only' mode and connect your own router downstream, for example to get better wi-fi coverage than the supplied device.

For a summary of the situation, see here


The only cable ISP in the UK is Virgin Media and they will require you to use the terminal boxes they supply as part of the package.

"boxes are useless without being registered and activated by Virgin Media for use on the Virgin Media cable network. You may as well be buying a brick and trying use it to access anything as buy one of those boxes. Virgin Media do not sell their STBs and the boxes remain the property of Virgin Media. Virgin Media will not activate a box unless they supplied it to a registered customer with an active account."


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.