My D855 (running 21A) cannot see 5Ghz WiFi hotspots

[mrjayviper]

So I just restored my phone to stock (21A KDZ) using the flashtool. I have no problems connecting to the 2.4Ghz WIFI hotspot but it cannot see the 5Ghz one. Each channel has a different SSID.

steps I've tried:
1. turning WIFI on/off
2. I've restored it to stock via flashtool twice
3. performed factory reset via stock recovery.

My Macbook and 6s+ are both connected to the net using the 5Ghz hotspot so that's not the issue. When the phone was running cm12.1, I had no problems seeing and connecting to 5Ghz WiFi hotspots.

Any ideas what could be wrong?

Thanks

 

[B. Diddy]

Is there an Advanced Wi-fi setting for Wi-fi Frequency Band?

 

[mrjayviper]

Is there an Advanced Wi-fi setting for Wi-fi Frequency Band?

not available on stock ROM. But it is available on CM12.1.

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I think the problem is the stock ROM. I just installed cm12.1 again and no problem seeing and connecting to 5Ghz Wi-Fi.
I also tried 20u and same results as 21a

 

[steveathome]

I have a D855 on stock (never been modified) with 21a. I have a BT HH4 and my phone locks on to 5GHz when I'm reasonably close to the router. At other times it locks on to 2.4GHz.