Hello kamran sorry to hear about your issues along with many other iPhone 6 users with same issue , I too had this issue tried everything from restore to reset network you name it I tried it so here's the fix , ok so I noticed I was having no service a lot and would only pick up very rarely searching so what I thought it must be a hardware fault as I tried everything everyone said and still nothing , so I decided to buy a new charging port and this is where things started to make sense so I got a new charging port and replaced it with a really cheap one say $4 but came with rusty tools and the charging port came without the two silver brackets which ground to phone , anyway fix it to phone and cappow sesrching come up and finally 1 bar of signal showed so my wife took it by window and signal was a bit stronger but still not as good as before so I bought an oem charging port which was $12 and this time came with the two silver brackets and could tell it was genuine anyway fitted this and what do you know full 5 signal bars 🙂 so honestly if you are out of warranty and can't fix signal issues I guarantee you this will fix it I know no one would expect this part to fail because my phone was still charging with no issues but it's the antenna wire connected to charging port that has failed if you have no signal or searching for network issues