It seems that some Bitcoin users have been reporting issues when attempting to connect or receive connections to their bitcoin clients across port 8333. Assuming that Bitcoin clients connect to other bitcoin nodes on TCP port 8333 by default, some of these users have strong suspicions that some ISP providers might have been intentionally blocking communications through and by this specific port.
The problem is said to appear when the ISP has complete control over the hardware from the user’s house to their router to the Internet. Many well-known providers will deliberately close a number of connection ports to facilitate what they presume to be the optimum level of service.
However, the reports points out that while some ISPs may indeed be blocking port 8333, they are not singling that particular port out but several others that might be affecting the so-called optimum level of performance.
If the user’s ISP does happen to block port 8333, there are a few solutions they can resort to. For starters, users can ask their ISP’s to put the router into “Bridge Mode”, which turns the ISPs hardware into nothing more than a simple connection to the Internet. A second option