Thanks for this and sorry to hear. The buffering is internet speed, processing speed (newest phones work best) and consistent internet speed.
Here's some solutions.
Go to the dashboard and use the speedtest to check speed. That will give you an exact number. We recommend 25 mbps on the low side. Think about the phone next and any options.
The other option is that we have a desktop/PC version that we can provide you with. The link is below. You use the same log ins and it accesses the same database so its "sharted" with your account on the app.
If the speed looks good and the phone new, send me your phone, the software version (from the settings screen and screenshots work well and are easy) and we'll add that to our dev file.
Let us know how that works and Good luck as you prep to pass the test!
Thanks!