DS-920+ causing internet interruptions with Deco X55

I’ve been troubleshooting intermittent loss of internet. I have Deco X55 x3, Main hooked to Cable modem and two others creating a wireless mesh in my home. Whenever I connect the DS920+ to the Deco (directly or through a switch) I get intermittent drops in my internet connection. Tech support from China has been a struggle due to hours and language. Tech emailed me today and said
"I guess that the NAS sent a flow control pause frame to Deco, which caused Deco to enter the flow control state. You can consult the technical support of NAS to see if there is a way to make NAS not to send pause frames. "

Does this make any sense? If so, any recommendations of how should I change my DSM networking settings? Currently running DSM 7.1.1-42962 Update 5