Hi all, I know it's my first post here but hopefully someone will help with my issue! The ensuite shower in my house was working fine for many years until it stopped draining a week ago. A small amount of water goes down but then stops as if it hits a blockage. I tried a (cheap) drain snake which didn't help and was giving up hope when I decided to disconnect the sink in the ensuite and WOOSH all the water drained right away! The shower works absolutely fine when the sink is disconnected, what is the issue? Seems to be something to do with drain pressure rather than a blockage. The ensuite appears to be on a separate drain line to the main bathroom and there is just the shower and sink, no toilet. I looked for venting on the pipe but I can't see anything coming out the roof other than the extractor fan in there which hasn't worked for months. Any help would be appreciated!