Slow loading with PikPak WebDav+Infuse Pro

I purchased Pro version and noticed loading videos are quite slow on Apple TV (4th, 128G) and Iphone-sometimes just stuck there for a long time. Tried retart both Infuse or ATV, no luck.
This is especially slow for 4k videos. I used PikPak webdav connection. And our
wifi should be more than enough-700-800m wifi download speed. Tried ethernet connection, no big improvement.
I tried Cache, Auto and No Cache in setting-seems no defference.
Speed tested-about 30-50m average for PikPak files.
Not sure if it is just with me or anyone has same issue.

Created case with customer service and wait for feedback/advice. Just to see if any user has any advice for this.

Thanks!

What version number of Infuse and also OS version numbers?

Infuse version: Infuse Pro 8.0.3(5007); ATV version: 18.1(22J580)