Research into consumers' understanding of broadband speed claims in advertisements is to be carried out by Ofcom.
The industry regulator will work with the Committees for Advertising Practice (CAP), which wrote and maintains the Advertising Codes.
Broadband providers can only advertise a headline speed if it is achievable by at least one in ten customers.
Guidance also states that any claims must be clarified with an "up to" qualifier, while those using ADSL2+ services must be told that their distance from the exchange can affect their speeds.
Ofcom said the guidance was drawn up to manage customer expectations and make sure they understand that numerous factors can cause speeds to vary.
The regulator revealed it has seen a 60 per cent drop in the number of complaints about broadband speed advertising since the guidance was introduced.
However, it pointed out that some consumers still feel misled by what providers are saying in their promotional material.
As a result, Ofcom wants to look at this issue in more detail and test people's understanding and expectations that arise from advertised claims.
Guy Parker, Chief Executive of the ASA, commented: "As an evidence-based regulator, we want to make sure our approach is underpinned by the experience of real people.
"While complaints to the ASA about broadband speed claims have reduced considerably over recent years, we’re taking action to respond to the concerns by testing our approach through consumer research."
Ofcom will publish its findings in the autumn, at which point CAP could determine if any changes to the current guidance need to be made.