You usually can't switch it from 5G to 4G manually, but only via network mode in the interface or by having 5G unavailable at the location. The device supports both 4G LTE and 5G SA/NSA and automatically switches to 4G if 5G is missing.

If there is a network mode in the web interface, search for a setting such as Preferred Network, Network Type, or 5G/4G Mode, and select 4G or LTE. However, this specific menu navigation is not confirmed in the available documents, so I'm not quite sure whether your model offers this option directly.

If you want, I can briefly list the most likely menu paths for the interface.

Can't remember how to do it anymore... it was really easy back then. I've also set it to 4G (230 Mb/s), as 5G is too slow (60 Mb/s)
You can do it, I bet