Much older iPads models support older WiFi specs and your alnost 9-year old iPad Air model will only support a WiFi data speed protocol UP to 100 Mbps download speeds, with that being highly variable based upon current Internet traffic, the amount of local devices accessing the WiFi MODEM/router network and other varaiables such local distnaces from your WiFi network and other magnetic or other physical device interference variables.
Also, Internet/ISP data travel distances from the nearest data transmission source to your home Wireless network can affect data download/upload speeds.