I've posted a similar request before, hoping that this kind of feature will be added someday.

It would be great if the vouchers can be stacked, and by stacking I mean multiple voucher tickets with the same or different time / rates can be combined into one, increasing the user's time to avoid getting disconnected. I know that we can manually add or extend that user's time, that's a good feature, but it would be very handy to have the stacking / combining of vouchers feature, another thing would be the ability to generate QR codes.

There's so many new controllers out there with this kind of feature, but I still prefer the omada controller, less pain in the ass.