I just rode a long support train with Sweetwater and PreSonus on this, and I'm going to give it you in a nutshell. I have had a Quantum 2626 for a couple of months now. At least once a day, it would randomly fall into fault mode and freeze up (froze up my iMac on several occasions, too). All the front panel input LEDs would suddenly glow solid red for 5 seconds, and then the unit would be effectively dead. Only a restart would bring it back. Ultimately, the problem was determined to be the cable. I was using the StarTech 2-meter passive 20 Gbit/sec cable that Sweetwater bundled with the Quantum. On the direction of PreSonus, I swapped that cable out for an Apple 0.8-meter active 40 Gbit/sec Thunderbolt 3 cable, and all my issues vanished. The cable, as it turns out, is a critical component in the use of an interface like the Quantum 2626. Find a way to get your 2626 closer to your Mac, spend the 40 bucks, and get that cable.
It's not the cable you want, it's the cable you need.