TalkTalk has been censured by the Advertising Standards Authority (ASA) after BT objected to claims it made on its website.
BT took issue with the statement that TalkTalk's Super Router delivers the "strongest signal and fastest speeds in the UK" and delivers "on average, 56 per cent faster speeds than routers from the other big providers".
The organisation argued that this was misleading and called for the claims to be substantiated, as not enough information was provided to verify the comparison claim.
The ASA stated that while it understood the method of calculation the provider had used, it was not clear how TalkTalk reached the conclusions made in the ad.
Indeed, the watchdog said its data actually appeared to suggest the average speed was less than 50 per cent faster than other firm's routers, as opposed to 56 per cent.
Furthermore, the ASA said that in order to make a general superiority claim, the testing needed to be representative of the activities generally performed by users.
The regulator has subsequently upheld BT's complaint and ordered TalkTalk not to publish the ad again in its current form.
"We told TalkTalk Telecom Ltd to ensure that claims accurately reflect the evidence intended to substantiate them and to ensure that they provided sufficient information to enable consumers to verify comparison claims," the watchdog said.