Why is my phone internet slow and sluggish?

Hi, I have an android phone {Vodafone Smart Ultra 6} and recently the internet is extremely bad. I am connected to Sky internet and I'm at a loss for what to do. I have reset my phone, changed accounts, checked for viruses and nothing seems to pop up. My internet works normally on my laptop, however, so I'm confused. When I change to my hotspot I can get things done on my phone but I don't want to waste my credit when I'm at home. Help?

🙋 A hardware fault with the phone, perhaps? Is it okay on other WiFi hotspots?