It likely doesn’t support 5ghz.

The IEEE 802.11ac is a wireless Wi-Fi standard developed within 2008-2013 to provide high-throughput connectivity across the 5GHZ band. The standard is an improvement on the earlier 802.11n wireless standard transmitting via the 2.4GHz frequency band.

Generally, a router that states it’s 802.11a/g/n, or 802.11ac will work at 5GHz. However, a router that is 802.11b/g/n has a slim chance of supporting that frequency, and you may need to upgrade. If your router supports 5GHz connectivity, the next thing to do is to check your adapter.

Table 7.5. 802.11 Wireless Standards IEEE Standard Frequency/Medium Speed 802.11a 5GHz Up to 54Mbps 802.11b 2.4GHz Up to 11Mbps 802.11g 2.4GHz Up to 54Mbps 802.11n 2.4GHz/5GHz Up to 600Mbps •Jun 9, 2009

The Realtek RTL8188EE only supports 2.4GHz 802.11 b/g/n. You will need a new WiFi card to connect at 5GHz. You need to change the network adapter.

Especially when it comes to the next big benefit of 802.11ac… So AC WiFi is much faster, but its peak speeds are not really the selling point. … In fact 802.11ac uses the 5GHz band while 802.11n uses 5GHz and 2.4GHz. Higher bands are faster but lower bands travel further.

802.11a supported the 5 GHz band and a theoretical maximum speed of 54 Mbps. In the early 2000s, many business/enterprise wireless devices used 802.11a Wi-Fi radios. The 5GHz bandwidths allowed for higher speeds than 802.11b and 2.4 GHz.

Switch to the Advanced tab. Select Band or Preferred Band option. Expand the Value drop-down list. Select 5 GHz only or Prefer 5 GHz band option.

Open iPhone’s main menu and go to the settings tab. Select the general settings field and tap on the reset button. Click on the reset network settings button and wait for the reset procedure to start. Once the reset has been completed, reconnect your iPhone to the 5ghz wifi band . . . Read more

The frequency band is changed directly on the router: Enter the IP address 192.168. 0.1 in your Internet browser. Leave the user field empty and use admin as the password. Select Wireless from the menu. In the 802.11 band selection field, you can select 2.4 GHz or 5 GHz. Click . . . Read more