Unless you have a really old system with a small hard drive, install the programs themselves ie Biab and RB, onto your system drive. The RT/RD's are fine on your external. I tested this some months ago because I had installed everything onto my SSD system drive but was running out of space so I deleted all the RT/RD's and ran them from the external. I timed it both ways and there was zero difference in rendering times.

As you just found out, digital audio is very tricky and COMPLETELY counterintuitive. What seems like a logical move isn't. Access violations, crashes, freezes etc will ultimately trace back so some kind of config issue either within RB itself or like your case your external interface.

Here's just one example. I had JUST written in the forum that I never get crashes with RB. Then I thought I had a crash immediately after I wrote that. Great, smooth move Sherlock. Turns out I had the Gain Change window open when I put the focus on the forum to check something. When I clicked on RB in the taskbar, that window was gone and RB was frozen. I remembered to look at the taskbar again and sure enough that Gain Change window had planted itself there. For some reason if you simply put your mouse focus on something else occasionally those floating windows will become unattached from the program itself and until you close that window it looks like RB had crashed.

That actually is a perfect example of what I had said. RB doesn't crash but it will do weird stuff like that sometimes. And in case someone thinks that's unique to RB go read the Cubase, Sonar, ProTools, PreSonus and anybody else's DAW forums. They all have weird crap like that because digital audio is extremely complex and tricky to work with.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.