If your machine is still draining slowly after cleaning the hose, the issue is likely in the wall plumbing.
For stubborn clogs, use a (also called a blow bag). Attach to a garden hose, insert into standpipe, turn water on. The bladder expands and shoots high-pressure water to scour pipe walls. Follow with another vinegar flush. best way to clean washing machine pipes
Use a long, flexible pipe cleaner or a bottle brush to scrub the interior walls of the hose. If your machine is still draining slowly after