Orchard House, near Sheffield United's Bramall Lane stadium, was rated 'inadequate' by the Care Quality Commission.
The watchdog has warned the home on Shoreham Street could be closed if improvements are not made within six months, after inspectors found six breaches of health and social care regulations.
The premises and equipment were not clean or properly maintained, people were not protected from the risk of financial abuse and medicines were not stored appropriately and at the right temperature, they found.
Inspectors described how people they spoke with had told them they felt safe and had no concerns about the service.
"We asked them how they asked for assistance from staff as they did not have a call bell to use in their room," the report states.
"They told us they just shouted, but described how staff didn't always hear them so they just gave up."
Residents spoke highly to inspectors of the manager, describing her as 'friendly' and 'very nice'.
But inspectors said more could have been done more to actively seek the views of relatives about how to improve the service, and records showed none of the staff had completed any training for supporting people with learning disabilities.
The service was deemed 'inadequate' for safety and leadership, and rated 'requires improvement' when it came to the other three categories of being effective, caring and responsive.
Orchard House, which supports adults who have a learning disability or autism, can accommodate up to 10 residents.
The Star has contacted Orchard House for a comment.
You can view the report in full at https://www.cqc.org.uk/sites/default/files/new_reports/INS2-2473654833.pdf.