RTL8722DM scan WiFi issue for 5Ghz

Hi, we are developing Wifi module board with rtl8722dm and have 5Ghz scan issue. The AMB23 SDK shows 2.4GHz and 5GHz scan results for "ScanNetworks " and “BLEWifiConfig” in sketch examples, but our board shows only 2.4GHz. Our board design or wiring is suspect to this matter.
We like to know how the arduino code checks the hardware wiring and cognize 5Ghz part not working. If someone knows code description, pls let me know and your support will be appreciated.
Thank you.

What RTL8722DM board do you use? could you post a link or paste a photo of it?

Sorry, it is a still developing board and cannot disclose the details and photo.
The design is similar to SDK board AMD23 , which show 2.4 & 5GHz scan results.
I wonder some configuration needed before use.
Thank you.

There is no configuration needed to use 5G wifi band, it’s enabled by default, provided your PCB design and antenna design are capable of 5GHz signal band

Thanks for your advice and understand 5Ghz can be used in default.
Is there any command somewhere in sketch to use 2.4 or 5Ghz, respectively if possible ?

nope, Ameba treat 2.4G and 5G all the same

Ok, thank you.
how about any special board/chip pin wiring related to 5ghz ?

@kkuma
I believe a RF diplexer is used to combine and separate the two RF bands onto one antenna.

Taken from the reference module schematics

Thank you for update. Let me talk to designer.

Hi, our designer wonders is there any reason that diplexer must be used. how about the circuit which conflating 2.4 and 5 GHz bands ? Is this causing any problem ?

Hi @kkuma
Antenna design is a very specific and higly sophisticated work, thus we advise you to consult the professionals in this field to get the most accurate response.
If you have contact to a Realtek FAE, feel free to contact them regarding the IC usage.

PS: This forum is more for the open source software/hardware discussion

Hi, xidameng
Thanks for your reply and yes, this is very specific matter as you mentioned.
Any way to send command for ic or board to check transmission power, or etc. ?

@kkuma
You may refer to the link below to access docmumentations related to Realtek AT Commands

Hi, Thank you, xidameng, I going to look through these files.