Missing solder pad and resistor R6700, headphones are not recognized

On the left of pin 1 of R6700 you have about 1 cm rail connecting the pad to the rest of circuit. Clean the area, use a good light source and some magnification and you’ll see the rail quite clearly. Scratch a bit its surface until you see the copper. Maybe there’s no need for a jumper either, unless you pulled the rail together with the pad, solder by itself should be enough to do the job properly. Temperature is way to low even for a solder iron, it should be in the range 290/320 if you use leaded tin , some more for lead free. That depends much on size of iron, station precision and so on..but 170C isn’t enough even to melt the solder wire.