Queue to limit bandwidth after 250mb of Traffic

Hi

I have a number of holiday cottages that are all sharing a single 4G connection via an SXT-LTE and a HAP-AC.

The HAP-AC provides DNS and DHCP for all users in the 192.168.88.0/24 address range.

What I would like to do is throttle all ips once they have used up 250mb of traffic in a 24 hour period to a slow speed (64kb for example). If possible a super user IP would be nice with no limits on it.

Is this possible using simple queues ? Any pointers to examples would be really appreciated.

Thanks

Nik

Anyone out there who could even give me a hint as to where to start with this one ?

I would be happy to pay for this / make a donation to a charity to get some help with this.

Check manual for connection-bytes in mangle rules