@SAW0548 

You would have to look at your network adapter on your Dell to see if it is possible for that computer to connect to 5Ghz.  If its only a 2.4GHz network adapter you would need a new network card.

  @Carl 

I did look and you were correct that my old network adapter only supported 2.4g.  I purchased a new dual band network adapter (Linksys USB6300), disabled the old adapter. 

Everything looked good but the new adapter would only hookup to the new adapter's 2.4g connection.  Talked to Linksys support, who advised that I setup the alternate network to just the 5g connection,  I did that and got the connection on the 5g, but my router seems confused in that when I try to read info from the router is enter 192.168.0.1 and the system can't find that router???  Also, to get the router to work with the Linksys adapter I had to specify the 2.4 channel (6) and the 5g channel (157).

  @SAW0548 

192.168.0.1 is regularly used as your internal network however it would also be other IPs as well.  You can open a command prompt on your PC, just search for CMD or Command Prompt.  on the window that pops up enter ipconfig and hit enter.  look for the default gateway and this will tell you the IP of your router.  

Alternativly to log into the AX21 you can open a web browser and type in tplinkwifi.net  that will act as a proxy for the IP of the router and get you to the sign in page.  

SdidAW0548 

Did the cmd prrompt and enter the default gateway address and got response that site can't be reached

SAW0548 wrote

SdidAW0548 

Did the cmd prrompt and enter the default gateway address and got response that site can't be reached

  @SAW0548 

From the Command prompt issue IPCONFIG /ALL, it should look like this:

==================

C:\ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Irxxxxxxx
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No

Wireless LAN adapter Wi-Fi:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Killer(R) Wi-Fi 6 AX1650i 160MHz Wireless Network Adapter (201NGW)
   Physical Address. . . . . . . . . : B0-A4-60-71-CB-40
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 26xxxxxx:4800:21ee::1008(Preferred)
   Lease Obtained. . . . . . . . . . : Friday, June 23, 2023 8:35:00 AM
   Lease Expires . . . . . . . . . . : Saturday, June 24, 2023 8:35:00 AM
   Link-local IPv6 Address . . . . . : fe8xxxxx554:ca3b%16(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.0.198(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Friday, June 23, 2023 8:34:59 AM
   Lease Expires . . . . . . . . . . : Friday, June 23, 2023 8:41:15 PM
   Default Gateway . . . . . . . . . : fexxxxxxx2:c44%16
                                       192.168.0.1
   DHCP Server . . . . . . . . . . . : 192.168.0.1
   DHCPv6 IAID . . . . . . . . . . . : 162xxxxx
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-xxxxx0-A4-60-71-CB-40
   DNS Servers . . . . . . . . . . . : 2001:1998:f00:2::1
                                       2001:1998:f00:1::1
                                       192.168.0.1
   NetBIOS over Tcpip. . . . . . . . : Enabled

=================

The BOLD lines are what are of interest. The IPc4 Address is the one for your PC.

The Default Gateway and DHCP Server are the ones that you should see and are the address of your Router.

I'm wondering if you have the RADIO off for the 5Ghz SSID OR you have SMART CONNECT enabled? If you do have it enabled, the router decides what band (2.4 or 5Ghz) it connects to, but the 2.4Ghz SSID is the only SSID used.