Stuttering 4K playback with Orbi RBK40 wireless backhaul

Thanks for the reply plemans.

Sorry I did not explain clearly. PC is only playing a storage role here, and 4K contents are saved in PC's local disk. It is a Wireless LAN transmission, thus I don't think this is any concern of the internet speed at all. 

I just ran a test to compare the performance between wireless and wired backhaul. The set up is as follows,

PC hardwired to RBS

Wired: RBS hardwired to RBR LAN1

Wireless: RBS wireless to RBR 

RBR LAN2 hardwired to LAPTOP

Iperf is used on both PC and LAPTOP to test the transmitting speed. 

Results:

Wireless transmitting speed: 23 MBps 

Wired transmitting speed: 110 MBps

While Orbi claims that 5GHz (866Mbps) dedicated WiFi link for faster data connections between Orbi router and Orbi Satellite. I only got 200Mbps.

Noted that RBS and RBR are not in the same floor, where RBR is in the utility room under stairs and RBS is in the study room next to stairs on the first floor. The distance is about 5 metres but there are wooden stairs and one wooden wall between them. 

The temperary solution is gonna be buying a long cable and making them wired, but my intension was using them wirelessly. lol

Any suggestions are welcome, any ways to improve the wireless backhaul speed are highly appreciated.