Started last night with mobile data and now even calling doesn't work. Worked perfect inside a VF store when I went to check if it's a SIM issue. Seems like antenna issue, works when very close to a signal source? Sometimes it shows GPRS instead of 4G. Handset was replaced by Apple out of warranty in Mar 2020 due to a bubble on screen & sometimes network issues but not to this extent. Have called Apple who have asked me to take it to one of the Authorized repairers but they haven't confirmed if they will cover it. Repair centre says I need to pay the inspection fee if Apple doesn't cover. Apple says they can look into covering repair cost depending on what repair center finds. Phone looks brand new, never dropped or gone near water. SIM works fine in another Android phone at the same location where I am. Alreazdy tried all types of reset, restores, Apple technician also tried remote diagnostic etc. Signal bar sometimes shows full with 4G, sometimes just one bar. Thoughts?