Relish Wireless has implemented an Acceptable Use Policy on its unlimited broadband service.
In its latest newsletter, the provider stressed that broadband should be unlimited without any data caps.
Indeed, it said it is "passionate about ensuring we can keep this for our customers".
However, Relish stated "really excessive use of the service can have a big impact on the experience for others".
This, it said, is particularly true during peak hours, when there are "lots of other people trying to use their broadband".
Relish is therefore putting an Acceptable Use Policy in place, which means some of its heaviest users that are affecting the network could be contacted and asked to reduce their usage.
"This just keeps it fair and ensures that everyone has good speed and access, rather than a few people essentially clogging up the network," the provider said.
"We will always keep an up to date explanation of our policy online if you want more information."
Relish added that 99 per cent of its customers will not be negatively affected by the change, and will in fact be likely to see an improvement.