Hi asidd_ and welcome to the RME user forum.

Probably the cable is too long now, according to the standard, the maximum supported length for USB3 cables is 3m, more is not possible. The cable supplied by RME is 1.8m long according to the manual (chapter 2), plus 2m makes a total of 3.8m. Even if your extension cable would be only 1.5m long, you exceed the 3m and that is known to cause problems.

If you check the driver settings (keep the dialogue box open so that CRC checking continues to run) then you might also see CRC failures counting up. Only zero error counters are acceptable. See also manual chapter 40.3.

If 3m is enough, get the Lindy Premium cable with triple shielding.

If you need longer cables, then a combination of an active Startech cable and a "passive" Lindy Premium cable will do. You require a suitable passive cable (USB3 type A / type B plug) because the Startech cable ends with a more generic type A not with a type B plug.
Further information and links to the products see my posting here: https://forum.rme-audio.de/viewtopic.ph … 04#p207204

As a side note, up to 2 of these Startech "active" cables can be connected in series so that the connection range can be extended to a total of 20 meters (plus the length of the passive cable). If necessary, the USB device can be powered by the included universal power supply and a wall outlet.

I would choose the length of the two cables so:
- enough clearance to move the equipment around a bit to swap boxes or check cables, my rack is on a rolling container
- the connection of active and passive cable should be strain relieved and not hang freely in the air

Manual references:
https://www.rme-audio.de/downloads/fface_ufx3_d.pdf
https://www.rme-audio.de/downloads/fface_ufx3_e.pdf

EDIT: Also an incompatible USB3 chipset could lead to audio dropouts, see also manual chapter 40.3.
Since there were no problems with the shorter cable before, I think this is unlikely.
But to be on the safe side, please check the shorter cable again with the CRC check in the driver settings.
If you see one of the CRC counters increasing, then you have transport errors even with the shorter cable.

In such a case, it is best, to try all USB3 ports of your system. This, because some systems also use 3rd party communication chips, where some might have issues with the transport mode that is in use with the RME driver. Best are usually the USB3 ports coming from the chipset (Intel or AMD) of your computer and 3rd party chips that have been tested and are documented in the manual.

Even if USB3 from chipset works fine it can happen that it starts to get issues the more USB2/3 devices you add to the system. I had this with my mainboard. Then it is advised to isolate the UFX III behind a dedicated USB3 PCIe card.

The one from Sonnet with FL1100 USB3 chipset is known to work very well and Windows 10/11 has drivers included in the system. https://www.sonnettech.com/product/alle … 4port.html