The RME MADIface driver works for me (UFX+) on Windows 11 (Test System).

Unfortunately you didn't tell anything about your system and in what situation / surrounding conditions the pops appear.
Proposal: would be useful to add some information about your system into your Forum signature.

Some checks:

- For UFX II: did you try already all USB2 / USB3 Ports on your system ?
- What are the LatencyMon results for your system if you run LatencyMon for 10 minutes on a freshly booted and otherwise IDLE system without any network / application load? https://www.resplendence.com/latencymon
- Do you see any CRC settings in the RME driver setting when having pops ? Keep this window open.
- How long is your USB2 cable?

Gathering more detailed information:

What CPU, mainboard/chipset, graphic card is in use? Any of the new hybrid CPUs ?
Have you installed all recent Windows 11 upgrades ?
Which Windows 11 version and build do you use ? Here Windows 11 Pro 21H2, build: 22000.318
Which RME driver and firmware version is in use (don't tell "the latest", real version numbers please).
Here: MADIface driver 0.9736 with USB HW revision 54 and UFX+ firmware version 46.

About the audio workload

Which audio application has the pops ?
Is a DAW in use, which one and which version ?
Does audio playback happen through ASIO or through WDM driver ?
What is the CPU load in this case ?
How is the ASIO load ?
What sample rate do you use ?
What are the settings for the ASIO buffersize in the driver, do the pops become lesser with higher settings, eg 512 at 44.1 kHz ?
Is MMCSS enabled or disabled in the RME ASIO driver, does it make a difference to activate/deactivate ?

About the DAW project (if applicable)

Any CPU hungry VST/VSTi in use ?
Many tracks, many inserts in a track ?
Is the DAW and are the VST/VSTi confirmed to run on Win11 ?
Did you make sure to use the RME ASIO driver in the DAW ?

Any potentially blocking drivers? High Interrupt load / context switch load

Is WiFi or Bluetooth enabled ?
Are you accessing the LAN / the internet when these pops / clicks happen ?

Which Windows performance tuning for audio happened so far ?

Did you perform the usual performance tuning to disable energy saving on your system
- BIOS: disabling of C-/P-/T-States, C1E
- BIOS: does a fix CPU clock help (disabling of EIST and maybe additionally TURBO)
  [usually EIST and Turbe can be kept enabled and then parametrize clock in Windows by using high energy profile and additionally disable CPU core parking ]
- Windows: if Desktop system: disabling of CPU core parking (Bitsum: parkcontrol tool, https://bitsum.com/parkcontrol/)
- Windows: selection of at least high performance energy profile and disable selective USB energy saving in the advanced settings ?
- Windows: if Desktop system: did you try ultimate performance power plan ? https://allthings.how/how-to-enable-ult … indows-11/, needs also disabling of selective USB energy saving in the advanced settings.
- Windows: did you try to priotize system for background applications