Windows 10 lacking function key actions

Hi Domi — sorry you’re hitting that. Let’s narrow this down and try a few fixes. Because you said multiple keyboards that “work” elsewhere, this points to the Windows IoT LTSC install / drivers / services or a firmware/BIOS setting on the machine rather than a bad keyboard. Try the steps below (I’ll list quick checks first, then deeper troubleshooting).
Quick checks (5 minutes)

• Reboot and try each keyboard in different ports (try a USB2.0 port if available, and plug directly into the PC — not a hub).
• If any keyboard is wireless (Bluetooth/RF dongle), test a wired USB keyboard as well.
• On the keyboard itself: try toggling the keyboard’s own FnLock (some keyboards use Fn+Esc or a padlock icon). Confirm the same Fn combos work on another computer (you said they do — double-check).

If those don’t fix it, follow this ordered troubleshooting:
A — Confirm HID services are running

• Press Win+R → type services.msc → Enter.
• Find "Human Interface Device Service" (hidserv). Make sure its status is Running and startup is Manual (Trigger start) or Automatic. If it’s stopped, right‑click → Start.
  Expected: once running, multimedia keys should be handled by Windows for many keyboards.

B — Check Device Manager for missing or faulty HID devices

• Win+R → devmgmt.msc → Enter.
• Expand "Keyboards" and "Human Interface Devices". Look for:
• "HID‑compliant keyboard"
• "HID‑compliant consumer control device"
• Any device with a yellow triangle or "Unknown device"
• For each keyboard entry: right‑click → Uninstall device (do this only for external keyboards). After uninstalling, unplug the keyboard, reboot, then plug it back in so Windows reinstalls drivers.
  Expected: Windows will reinstall proper HID drivers and consumer control device entries; Fn multimedia should start working.

C — Check for special vendor drivers / firmware

• If these are branded keyboards (Logitech, Razer, Microsoft, etc., they sometimes require vendor software/firmware to enable Fn multimedia features. On IoT/LTSC images those packages may be missing. If you have a keyboard brand, tell me which and I’ll point to the appropriate firmware/driver installer.
  Warning: vendor software can modify system behavior — create a restore point first if you’re on a production device.

D — BIOS / UEFI function key behavior (if it’s a laptop or an OEM motherboard)

• Reboot into BIOS/UEFI settings and look for "Function Key Behavior", "Action Keys Mode", or similar. Some systems let F1–F12 default to multimedia actions or require Fn to be pressed for multimedia. Toggle the setting and test.
  Expected: if the firmware is toggled the wrong way, you’ll see different default behavior from the F‑row.

E — Test whether Windows receives the key events

• If you’re comfortable, create a new local administrator account and log into it to rule out user‑profile remapping issues.
• If utilities are okay, try a simple key‑event tester (or a Linux live USB) — if the keys work in a Live USB, the issue is definitely Windows configuration.

F — Look for remapping / filters

• Some corporate/enterprise images add keyboard filter drivers (e.g., keyboard filter for kiosk mode) or registry scancode maps that block consumer control keys. If this device was provisioned, check for installed "Keyboard Filter" drivers or check the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout\Scancode Map for remaps (I can walk you through checking this safely).

If none of the above helps

• Tell me:
• Is this a laptop or a desktop?
• Are keyboards wired USB, USB dongle (wireless), or Bluetooth?
• Does Device Manager show any unknown/HID devices or errors? (If you can paste the exact names shown under Keyboards and Human Interface Devices that’ll help.
• Any vendor name/model for the keyboards (Logitech K840, Microsoft Sculpt, etc.?
• Is this device managed by an organization (kiosk mode / group policy / custom IoT image)?

What I’ll do once you reply

• Tell you exact Device Manager entries to remove/reinstall and registry checks, or give vendor driver links and step commands. If needed I’ll give step‑by‑step commands to capture the HID events so we can prove whether Windows is seeing the Fn multimedia scancodes.

If you want, start with A and B and paste back the names you see under Device Manager → Keyboards and → Human Interface Devices. I’ll guide the next step from there.