Wireless 5ghz - Trouble shooting

When i first set up my router, I put the latest merlin firmware on and setup the dual band wireless. When using dlna programs to share files on my phone, I saw through the traffic manager that the 5ghz was being used. My problem now is that this band is not being used anymore even though I have it on.

Would someone trouble shoot met on how I can get this band to be utilized for my file sharing network? Or point me in the direction where I can find help.

Thanks in advance.