RBK40 reserve IP address

Hi

I have a Orbi RBK40 mesh system with a RBR40 and a RBS40

I sometimes have issues with streaming on two smart TV's (a Samsung and a LG) which are respectively quite close to the router and the satellite.

The image freezes for few seconds quite frequently

The signal is very strong and I can't work out what the issue is.

Is it worthwhile reserving an IP address to each? If yes how do I do it please?

Any other ideas regarding what the problem might be? 

Someone suggested tuning the firewall off but I don't think it can be done with the Orbi.

Thank you