HDMI cable to TV

Trying to play Netflix on an older TV for my mom who is a housebound senior with no internet. Android phone and cable work fine. Iphone HDMI cable tv to phone we hear the sound, but no picture. Any thoughts? We tried different Iphones and an Ipad with same result. Once we did get a picture with a $50 iphone adapter and then plugged in an HDMI cable, but it was phone size and would not expand. Thnx