@Pronoy009 

Hi,

This issue has come up before.

If I remember correctly the thing is that the government of Bangladesh only allows the use of channels 149, 153, 157, 161, 165 in the 5 GHz band.

On the other hand, due to the regulations in Europe the routers for the European ("EU") market don't support channels 149, 153, 157, 161, 165.

That might be the reason why your Bangladeshi devices don't see the 5 GHz SSID of your TP-Link Archer AX23(EU), since it will be operating on channels 36, 40, 44, 48.

What kind of devices do you have?
In case your devices allow manual selection of a country or region, then you could try to set it to another one (for example United Kingdom) and see if that may "trick" the device(s) into using channels 36 to 48.

  @woozle 

I'am currently using a custom rom and it has no region selection option

Note :- My router and phone i bought them both in the united Arab Emirates.

  @Pronoy009 

If you are sure your smartphone is able to use channels 36-48 (which I guess it should if it's from the UAE), then try the following test.

Restore your Archer AX23 to factory default settings, either via the router's web management page or by pressing and holding the physical "Reset" button for > 6 seconds)
Wait until the router has booted up following the factory defaults restore and then check on your phone if it can see both default SSIDs as shown on the label on the underside of the router. (something like TP-Link_xxxx and TP-Link_xxxx_5G)

If TP-Link_xxxx_5G still doesn't show up, then there isn't really anything else you could do.