Hi  @Marjatta 

You may enable Smart connect feature before, so you can only see one Wi-Fi at home.  With the Smart Connect feature enabled, the TP-Link router will combine the 2.4Ghz and 5Ghz Wi-Fi into one. To distinguish the 2.4G & 5G Wi-Fi, please log into the router's web interface, go to Advanced> Wireless> Wireless Settings to disable it, and set different Wi-Fi names.

If you can see two Wi-Fi names separately, but only can connect to 2.4Ghz or 5Ghz, please try the following steps:

1. Reboot router. (Power off and power on again)

2. Change the channel and channel width of the abnormal frequency:

Changing Channel and Channel Width on a TP-Link Router (new logo)

3. Hard reset the router and test further:

How to reset TP-Link router to factory defaults

If you are experiencing difficulties with the Tether app detecting your TP-Link Archer Router, please follow the steps below:

    1. Make sure your device supports the Tether APP. Routers that support Tether app can be found here: https://www.tp-link.com/tether/product-list/

For the Wi-Fi router, please note that only Router and Access Point modes are compatible with Tether APP.

    2. Make sure the phone is connected to the main network of the TP-Link device, not the guest network or other networks.

    3. To upgrade the TP-Link devices' firmware to the latest version, you may log in to the TP-Link web management interface to check for updates.

    4. Turn off any VPN application on your phone.

    5. Turn off the mobile/cellular data on the phone.

    6. Reboot the TP-Link device.

    7. Close the Tether app completely (kill it in the background) and reopen it.

    8. For iOS devices, please enable "Local Network Access" permission for the Tether APP (Settings > Tether APP > enable Local Network Access).