You likely have "Band Steering" enabled. The router tries to force you onto 5 GHz. Turn off "Smart Connect" in the admin menu. Create separate SSIDs (e.g., "MyWiFi_2G" and "MyWiFi_5G"). Connect your phone to the 2G network when moving far from the router.
To understand the significance of Wave 2, one must first look at its predecessor. "Wave 1" typically referred to the initial rollout of high-speed public Wi-Fi hotspots, operating primarily on the 802.11n or early 802.11ac standards. While fast, these networks often struggled with congestion in crowded areas. kt giga wifi wave 2