4G not working on iPhone 8 plus
I bought an iPhone 8 plus in november and after about 6 weeks the data started to slow down. It shown an E instead of 4G and it just didn't work or it was very slow. This only happened at home so I thought that maybe the SIM card is the problem but I put it in my iPhone 6 and then it was fine. I called the service and did everything they told me to but nothing worked. I returned it. They told me that they couldn't fix the problem so they gave me a new one. After three weeks the new one had the same problem. I returned it but now they said that they can't find any problem. Any advice?
iPhone 8 Plus