BT has been told to stop showing its TV adverts for the Smart Hub after the Advertising Standards Authority (ASA) ruled they were misleading.
Last summer, BT launched new ads for the Smart Hub that claimed the devices offered "the UK's most powerful Wi-Fi signal" capable of reaching "some serious distance".
However, the likes of Virgin Media, Sky and TalkTalk subsequently complained to the ASA about the commercials, arguing that the claims being made were misleading.
BT insisted that it undertook extensive testing of the Smart Hub before making the claims in its advertising.
Furthermore, it said the ads included qualifying text on-screen to back up the statement that it offered the UK's most powerful Wi-Fi signal, making it clear that the device was being compared against other major broadband providers.
The ASA accepted this argument, but determined that the headline claims were "very broad and would be understood as whole-of-market comparisons".
Additionally, it ruled that while the qualifications in each ad did outline the basis of the comparisons, they were not prominent enough to "counter the overall impression that the comparison was against the whole market".
The ASA has therefore ordered BT not to show the adverts again in their current form.
"We told BT to ensure that they made the basis of comparative claims clear in order to avoid giving a misleading impression to consumers," the watchdog added.