XPS 13 9350 Wireless Speed Limitation

I have an XPS 13 9350 with a Dell Wireless 1820a 802.11ac network adapter.  I have searched the Dell community and online in general but cannot seem to figure out why my I'm getting limited download speeds from this machine.  I cannot seem to surpass about an 18 to 20 Mbps download data rate.  I don't have Killer or SmartBytes (both which have been mentioned in similar threads).  Here's what I've done so far to troubleshoot:

• I have all the latest drivers/updates from Dell and from Windows (running most current Windows 10 Pro build) and done appropriate restarts
• I connected my XPS to 4 different wireless networks and did speed tests, all of which are repeatedly giving me speeds no more than 20Mbps (no matter the time of day or location)
• On my home network, I did side by side comparisons of this Dell XPS, a 2013 MacBook Pro, a Samsung Android phone in airplane mode, and an iPad.  I used the same speed test on all devices at similar times and locations around my house.  All devices match up on the UPLOAD speeds but the Dell is consistently not hitting more than 20Mbps.  My other devices are pulling 120+Mbps in similar scenarios.

It seems like something is throttling back or limiting my XPS wireless adapter but i can't figure out what.

Any suggestions would be very welcome.

Jered