TP link C6 v2 Router's antenna identify

i have a tp link C6 v2 (US) router.
there are 5 antennas.
one is internal and other 4 is external.
I found that 2 external antennas are soldered with PCB
and other two external antennas are connected with PCB by two small connector.

Can you tell me witch Two antennas are for 5 ghz channel?

The two back ones on the right.

Thank you.
If you don’t mind me asking, could you please tell me how you know that?