Thought it might be helpful to first explain the problem that requires me to block an IP range.
Over the last couple of weeks I've found it impossible to watch unpopular HD videos on Youtube. As I'm watching I can see the grey buffering bar move along as the video is downloaded, but after approx 2 minutes the video stops downloading and after a couple of seconds the bar moves to the end. I hope you know what I mean when I say 'grey buffering bar' as opposed to red actually watched bar.
After a bit of research it appears my ISP TalkTalk (in the United Kingdom) is caching Youtube videos but something is going wrong. This [link] explains why ISP's cache youtube videos. If I go to view a popular video there is no problem and I assume that is because it's already cached, but a new video fails and I assume something has gone wrong with the caching process. If I keep refreshing the page for the failing video then each time a bit more downloads than before, and once it's completely watched there are no problems in the future.
Last night I confirmed the ISP was delivering the video using Kaspersky Network Monitor. The IP address a video was being delivered from was for my ISP rather than Youtube [link].
I created network rule for my browser to block the address, hoping that it would force a connection to Youtube, and it worked. When I refreshed the page the video now downloaded from Youtube with no problems.
Unfortunately there is not a single IP address to block. So far I've blocked the following.
So it looks like I should block everything after .154, Guidance on how to block an IP range can be found here .
Unfortunately it's too difficult for me to understand this CIDR stuff. I expect my ISP to fix the caching problem, but in the mean time what do I enter to block the range above .154 ?