A growing number of Tiscali broadband subscribers are expressing their discontent with the service after problems were reported relating to web-connected games consoles.
Users of the Sony PS3, Xbox 360 have reported difficulties connecting to play online against friends or family.
Those attempting to play games online via PCs have also experienced blocked connections.
The broadband providers' customers have also voiced their concern at what appears to be a blocking of peer-to-peer services on certain sites.
According to PS3 Daily: "Ok working online going onto websites etc is totally fine, but when it comes to gaming online this is a whole different kettle of fish.
"There seems to be a growing dissent among the subscribers [of] Tiscali, many have claimed that Tiscali is in breach of contract for exercising port and service blocking."
Reports suggest that the issue has been discusses by disgruntled gamers on thousands of internet forum pages.