Data to/from hotspot login page counted in Accounting

Hello,

I have setup a hotspot using routeros on a Virual Machine. All that works perfectly fine. I can login / logout / check status etc. However when a user logs in to the hotspot, the data that is transfered from the login page to local network is also accounted which is not desirable. Ideally only data which flows through the wan port should be counted instead.
This problem is further compounded as I am using a Bootstrap html and the .css .js files (stored on router /hotspot folder ) which are significant in size ( 400 kb each refresh ) are all counted in Data downloaded.
I have seen several videos online and this does not seam to be the problem any where. I can see that there data is accounted for correctly.
Is there anything I have been missing or any firewall / nat rule needs to be added ?

Any leads would be much appreciated.

Thanks