Chosen Solution
I have bad cellular reception, however wifi works good. Which antenna should I replace? Top left or right down. Which one is cellular, which one is wifi? kr
Both you mentioned are primarily for Wifi, the cellular antennas are the top and bottom end of the case. There are contact points on the board, screws and contact prongs connect them to the board. Also there are RF jumper wires connecting the upper end of the board to the lower half where the cellular parts are. Bad cellular reception troubleshooting depend on what bands your carrier is using, did you mess with the case, the screws or the board. This can be highly complex as iPhone now use both antennas at the same time to connect to several bands at once to maximize download speed.
