Transferring photos from a Nikon Z50 with Airnef/PTPIP program is slowing down until disconnection

Question

I am using Airnef (and the PTPIP protocol) to download pictures from my Nikon Z50 camera through Wi-Fi. It works perfectly in some cases, but in other cases the transfer is slowing down until the camera has been disconnected.

I have read the associated documentation (available here https://www.testcams.com/airnef/) and seen that a similar issue has been encountered while the program has been developed, which seemed to be caused by a bug in the Nikon firmware which lead to some memory issues and a possible disconnection. The same issue seems to have been found during gphoto2 development (https://sourceforge.net/p/gphoto/mailman/gphoto-devel/thread/20190107075304.GC4614%40jet.franken.de/)

From what I understand, the parameters "maxgetobjbuffersizekb" and "maxgetobjtransferzekb" have been introduced to fix a such issue by trying to limit the requested sizes on the camera to transfer image, however it does not seems to work in my case.

I have tried to customize the values used by these parameters (for instance, by using a value of 256kb for maxgetobjtransferzekb setting), but with no real luck (the connection seems to abort less often but the transfer is still slowing down).

Here is an extract of the trace I get when I increase the log level in airnef.

Download history file "C:\Users\aerkis\AppData\Local\airnef\appdata\Z 50-SN6026496-downloadhist" loaded - 2 entries
Skipping DCIM - object is not file - MTP_OBJFORMAT_Assocation (0x3001)
Skipping 101NZ_50 - object is not file - MTP_OBJFORMAT_Assocation (0x3001)
>> MTP_OP_GetObject
Downloading "DSC_0490.JPG":  0%DSC_0490.JPG - downloading next piece, offset=0x0, count=0x100000
execMtpOp: MTP_OP_GetPartialObject - CmdReq payload:
0000: 06 00 00 00 01 00 00 00 - 1b 10 0b 00 00 00 ea 41 ........ - .......A
0010: 19 29 00 00 00 00 00 00 - 10 00                   .)...... - ..
execMtpOp: MTP_OP_GetPartialObject - DataStart payload [expected data bytes is 0x100000]
0000: 09 00 00 00 0b 00 00 00 - 00 00 10 00 00 00 00 00 ........ - ........
 0%execMtpOp: MTP_OP_GetPartialObject - Data payload [ID a] (0x00005b3c bytes):
0000: 0a 00 00 00 0b 00 00 00 - ff d8 ff e1 ff fe 45 78 ........ - ......Ex
0010: 69 66 00 00 49 49 2a 00 - 08 00 00 00 0d 00 0f 01 if..II*. - ........
0020: 02 00 12 00 00 00 ac 00 - 00 00 10 01 02 00 0b 00 ........ - ........
0030: 00 00 c0 00 00 00 12 01 - 03 00 01 00 00 00 01 00 ........ - ........
 1%execMtpOp: MTP_OP_GetPartialObject - Data payload [ID a] (0x00005b3c bytes):
0000: 0a 00 00 00 0b 00 00 00 - 4f 00 72 a5 99 4e c4 fb ........ - O.r..N..
0010: f3 a3 26 61 66 1d 98 d7 - d7 98 1a 5d cc 26 ac f3 ..&af... - ...].&..
0020: f3 c4 4e 99 a5 72 00 4f - 5e 30 c2 15 12 f9 94 eb ..N..r.O - ^0......
0030: 03 dc 76 d1 ed ca 68 c7 - e7 c8 6a cd f1 d6 7c e3 ..v...h. - ..j...|.
execMtpOp: MTP_OP_GetPartialObject - Data payload [ID a] (0x00005b3c bytes):
0000: 0a 00 00 00 0b 00 00 00 - 00 00 00 00 00 00 00 00 ........ - ........
0010: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ........ - ........
0020: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ........ - ........
0030: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ........ - ........
 2%execMtpOp: MTP_OP_GetPartialObject - Partial payload after error (0x00004329 bytes):
0000: 0a 00 00 00 0b 00 00 00 - 20 20 20 20 20 20 20 20 ........ -
0010: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0020: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0030: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0040: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0050: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0060: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0070: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0080: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
0090: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 20 20          -
DSC_0490.JPG - error during download, writing 0x0 bytes of buffered data
DSC_0490.JPG - writing partial payload data of 0x154bd bytes
C:\Users\aerkis\Pictures\DSC_0490.JPG writing 0x154bd bytes, closeAfterWriting=0
MTP_OP_GetPartialObject: Socket error, partial data received - 0x4321 of 0x5b34 bytes for specific payload, 0x154bd of 0x100000 of total data bytes expected. Error: timed out

Therefore, I request some help to know if it exists a way to better understand this problem and possibly correct it (maybe by configuring some parameters ?).

Any help would be greatly appreciated !