I'm having trouble with iphone retaining internet connectivity with the BE900.

While wifi is working fine for other devices like my computer, the wifi stops working on our phones every now and then. In order to make it work again, I have to disconnect from the wifi from my phone and reconnect to it.

The phones are not using he 6GHz network.

This didn't happen with the old ISP's router.

I can't say for sure since I hadn't used it long, but I think this problem exaggerated after the latest firmware update.
Is this a bug or are there any settings in the router that aren't set up properly?