Posting this while in the middle of a THREE HOUR call with technical & customer support. I'm connecting my TB16 to an Alienware 15 R3 and the TB16 has issues with USB peripherals (mouse, keyboard, and audio interface) where it would disconnect periodically. Sometimes it would work for a week, sometimes for only 10 seconds...extremely inconsistent. BIOS and Drivers are all up to date. So I basically connect my peripherals directly to the laptop, and use TB16 for display port and ethernet.
Prior to purchasing the TB16, Dell confirmed that it would work with my AW 15 R3. I finally called Dell tech support to resolve this issue, but they sent me to Alienware Premium support because they say this is an Alienware issue. Alienware then say they do not troubleshoot Dell docks at all and sent me back to Dell support, who (not surprisingly) say they can't solve this issue because it is an Alienware issue. So all this back and forth, from speaking with 7 different reps, I finally get sent back to Alienware premium support team again, and they tell me that Alienware do not support the TB16 and that they ABSOLUTELY cannot help at all. My biggest gripe is that no one is taking responsibility for this and I'm being passed along from 1 rep to the next. (I almost think I'm on the phone with Comcast customer service)
I'm past 30 days for a return and refund, so they only option I have now is to exchange it for another TB16 and pray that my original is a lemon. I'm almost certain that the replacement won't work either but I'm out of options.
Some recent BIOS updates for various systems have caused intermittent disconnects and reconnects for USB devices attached to TB16 docks (and I think I've seen the WD15 mentioned too, but I can't remember). There are several threads on this topic right now just in the first page or two of this forum because they're all very active. Unfortunately, downgrading back to an earlier BIOS does NOT seem to resolve the issue, perhaps because some component that's updated in the BIOS update can't be (or simply isn't) downgraded even when the main BIOS firmware is. The good news is that Dell has acknowledged the issue, and just today a Dell rep advised that a new BIOS update currently being tested internally appears to have solved the issue and should therefore be released shortly. That thread admittedly pertains to the XPS 13 9360, but since this problem was introduced on several systems at around the same time when they all got BIOS updates, it's reasonable to expect that the fix will come for all affected systems around the same time.
So if you haven't already, don't bother sending your TB16 in for an exchange. It will very likely prove a waste of time -- and if you DO somehow turn out to have a lemon TB16, presumably your warranty will still be active after the new BIOS updates are released, so you can do the exchange then.