Accessing USB sticks on HP Elite t655 thin client running ThinPro 8.1 (SP 3.5)

[Blabberhoof]

I am currently evaluating possible Thin Client replacements and I'm trying to get one test client to work.
Base system is a HP Elite t655 Thin client running ThinPro 8.1 (8.1.0-66121, SP 3.5).

I tested extensively with an modified image and with the plain vanilla image provided by HP.

The aim is to connect to our Terminal server farm (Server 2016) and to be able to access locally plugged mass storage devices (mobile phones, usb sticks).
When trying the same from a windows workstation, the usb redirect runs smoothly (so it shouldn't be user settings or server side problems), when I try the same with the thin client, I don't get any result.

Of course the device classes in usb manager are allowed, the redirect protocol is freerdp2, redirection is either high level or usbr (tested both).

Logs on the server indicate that the client never sends any information about connected devices, the thin client itself recognizes the usb devices (at least lsusb shows it).

[Blabberhoof]

Okay, I got a bit further on that topic.
I got USB keys / sticks now working with FAT32 and NTFS (out of the box) and exFAT (with a bit of manual hassle).

The issue there was that the usb stick was initially formatted as exFat and the initial NTFS tests were done without extensive plug/unplug sessions and reboots for good measure, but while the system was running.

The big issue still are mobile phones.

I tested Motorola Moto G30, Motorola Moto G54 and Samsung Galaxy S20 - didn't try Apples yet.

The device gets recognized (in lsusb) after activating data transfer mode:

---< snip >---

Bus 001 Device 004: ID 22b8:2e82 Motorola PCS XT1541 [Moto G 3rd Gen]

---< snip >---

but there are no devices to mount available.

Here's syslog after plugging in the mobile:

---< snip >---

Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.177082] usb 1-2.4: new high-speed USB device number 9 using xhci_hcd
Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.333158] usb 1-2.4: New USB device found, idVendor=22b8, idProduct=2e82, bcdDevice= 4.19
Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.333170] usb 1-2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.333174] usb 1-2.4: Product: moto g(30)
Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.333177] usb 1-2.4: Manufacturer: motorola
Aug 28 13:14:41 lw-tc-edvtest kernel: [ 4786.333180] usb 1-2.4: SerialNumber: ZT3225CG6P
Aug 28 13:14:41 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session starting for pid 12400.
Aug 28 13:14:41 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session closing for pid 12400.
Aug 28 13:14:41 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session starting for pid 12400.
Aug 28 13:14:41 lw-tc-edvtest citrix-ctxcwalogd[1133]: Process 12400 has named itself "citrix-ctx_usb_isactive".
Aug 28 13:14:41 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session closing for pid 12400.
Aug 28 13:14:42 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session starting for pid 12467.
Aug 28 13:14:42 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session closing for pid 12467.
Aug 28 13:14:42 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session starting for pid 12467.
Aug 28 13:14:42 lw-tc-edvtest citrix-ctxcwalogd[1133]: Process 12467 has named itself "citrix-ctx_usb_isactive".
Aug 28 13:14:42 lw-tc-edvtest citrix-ctxcwalogd[1133]: Session closing for pid 12467.
Aug 28 13:14:57 lw-tc-edvtest ftscanhvd: protocol/discovery/avahiDiscovery.c 136: failed to start service : Unit avahi-daemon.service not found.
Aug 28 13:14:57 lw-tc-edvtest ftscanhvd: protocol/discovery/avahiDiscovery.c 472: Failed to create client object: Daemon not running

---< snip >---

[Blabberhoof]

HP's official support solution for the problem is:

"ThinPro uses Linux and therefore this function is not supported. It may come somewhen in the future, but it's not guaranteed."

Dear HP... that's a big steaming pile of manure, to be honest.

Linux is most definitely able to communicate via MTP.

ThinPro is a distribution by HP, so it's up to HP to select software carefully and present usable configurations. You guys can't tell me that accessing files on mobile devices via MTP is such a novel concept that nobody ever would need that.