Hi,
I want to limit quota on my wan interfaces.because of my wan interfaces is volume base.

Bump. Still relevant. for backup LTE links. I set up 128 kbps bandwidth limit but I calculated that it can still pretty easily use up whole per-month 10 GB data limit in around 1 week.

You may be able to "bodge" this by setting up your LAN as a hotspot client and limiting data used that way? Very long winded way around doing it but should work.