UPDATE: Happy to report that replacing my Linksys EA9500 router with an ASUS RT-AX88U AX6000, turning on Adaptive QOS and prioritizing Streaming Media fixes the problem so effectively that I am now able to watch two simultaneous NAS to Kodi box streams of Lucy (4K Remux), WITH 100MB/s download going on. In real-time, the router essentially deprioritizes the 100MB/s download to about 80MB/s and the streams both are 100% stable. I'm shocked. Not to mention, with WIFI 6 speeds, I'm getting over 500mbps from the router to my computer which is in the same room.