5Ghz Wifi works but not 2.4

[beyerstefan]

I received my modem for the 4G broadband internet.
In the modem (tp-link AX5400) it seems like I can only configure 1 main Wifi SSID for both 5GHz and 2.4GHz?
So all my IoT devices (2.4GHz) could not connect !
Even if I am setting up a Multi-SSID (which seem to be separated for 5/2.4GHz) they can't connect. Only after I enabled the 'allow guests' for that SSID they could connect and are show as 'guest'. But they certainly do have credentials (SSID and password)
How can I configure the main SSID for 2.4GHz ?

[BasilDV]

Hi @beyerstefan

Thanks for raising this with us.

Are you able to provide a screenshot of your WLAN/Wireless settings? We'd like to check on this further.

BasilDV

[beyerstefan]

Sure. I will.
At the moment I am struggeling to securely connect to my internal network from outside. I just seem to have hit a dead end with CG-NAT and no portforwarding possible since ther is no public visible IP address provided.
If that is the case I can't use the 4G broadband adn the 2.4GHz problem will be obsolete.