Just did a fresh install of Debian 10.3 with KDE Plasma on my Dell Latitude. Getting things fixed up and decided to work on a new youtube video. I plugged my Android phone to the laptop to begin the video file transfer so I can edit the video file on the laptop. Dolphin picked up the phone connection through USB and it popped up showing me the files/folders. So browsing my phone worked fine. But as soon as I attempted to copy the video file over it spit out an error that it could not read the file. Tried numerous times with the same result. I thought maybe it was my cord/phone port b/c I must have a little bit of dirt/debris in the phone port and sometimes the connector can get loose and lose connection. Double and triple checked the connector and it would still get an error when trying to transfer.

NOW, I did come across a thing called KDE connect and was able to transfer my video file that way. It worked, but it was a slow transfer (video file was about 800MB). Most of my video files are pretty big anyways.

Any ideas as to why dolphin/KDE was having issues? I did do some reading and apparently there have been problems with it in the past. Any other alternative ideas to where I can still use the USB cord? Any way to speed up KDE Connect (except maybe upgrading my router)? Any other alternative options I could try?

There is a menu with the connection-mode (or whatever it is called) in android / lineageOS when you swipe down from the top. It defaults to a non-transfer (charging) mode at least on my Moto G3. Try to change that to file transfer.

Unfortunately I've made sure of that too. Mine most always stays on file transfer.

Long shot: user / group / permissions crossed? I had that problem some time ago but forgot the solution I used then. Nowadays I exclusively use KDE-Connect, on my machine it is quite fast. Did you check your WLAN parameters?

As for WLAN, I'm on a Windows laptop right now and it's wifi speed is 130Mbps. I'm going to assume that the Linux laptop is about the same. Router is a Buffalo WZR-HP-G300NH. Honestly, we've had the router about 10 years now (still going strong) and I am thinking of upgrading it here soon anyways.

OK, I just found out, if I import through a program called Gwenview the videos transfer over fine with the USB cable.

An alternative solution is to install an FTP server app on the phone. it's generally faster than MTP. The app I use is called primitive ftpd. The only limit is WiFi speed.

Well, I use Gwenview for photos, wouldn't have thought of transferring videos with it.

Now, I'd really like an explanation for the effect you observed ... somehow all our technology seems to remain in an experimental stage. *sigh*

I was reading that a few years back folks had similar issues with smartphones and transferring files via the cable and using mtp and KDE.

When I plugged up my phone it gave me 3 options...2 of them were browse the files with dolphin (which oddly enough each one was a different set of directories...guess my phone had 2 partitions in storage)...and the other was Gwenview. As soon as I would find the file, copy it, and then make an attempt to paste it to the new location it would give that error.

Gwenview gave me the option to import whichever pics/videos I chose from. It imported the video pretty quickly actually, defaulted it to Downloads, and renamed it to the file's timestamp.

Gwenview didn't seem too bad to use. I may end up using it OR I may switch to something else. Just wondering if anybody had heard of a fix for the whole mtp thing.

If you can connect the phone via USB cable, I recommend setting up adb and use that ('adb pull') for large file transfer.
It's little work to initially set up and much faster than mtp or any other solution.

I was wondering about why you don't try Kdenlive. That is a video editor after all. Might be more appropriate and helpful in your case (apart from the adb). Still, there must be a reason why copying is slow with dolphin and fast with Gwenview...

I looked a little bit into adb...attempt a pull transfer of a sample file but even it gave me errors. as well. Don't remember the specifics, something do with device/emulator. I do kinda prefer doing this with a GUI anyways, so I can see a thumbnail of the image/video before I transfer it.

I tried a few different file managers and didn't have much luck with them which I thought was strange. Perhaps it was some parts of KDE still running while trying out a different manager. I do remember seeing an error pertaining to KIO as well.

I have now reverted back to using the Cinnamon DE where it works fine. I'm pretty familiar with the Cinnamon environment (and I like the layout of it as well) from when I was using Linux Mint. Plasma was pretty cool and if it weren't for the smartphone/MTP thing I'd still keep using it. Personally I do think that's a big deal breaker for the desktop environment...I would think most environments should have a quick option for extracting files from your smartphone using the USB cable. So I'll use it this way for now. Perhaps once I get our router upgraded to something a little peppier, I'll look into using FTP.

Seconding this. I've been using ``AndFTP'' to transfer music files to my phone and it a much easier process than fiddling with the USB connection which seems to be geared to photo transfers and getting the phone seen as a generic storage device is a hassle. I seem to get about 4MB/s on average (when I'm not competing with my daughters' streaming habits). It's not superfast but I can have files moved in less time than it takes to convince the USB connection to work the way I want it to work.

You do have to running the ssh service on your computer for this to work. That shouldn't be a problem to enable if it's not already running.

HTH...

Yup, exact same setup here. I use the scp profile. Works absolutely great.

Sorry about that; adb does sometimes require initial setup (something about udev rules for android devices).
Once set up, the transfer speeds compared to MTP are unbeatable. I bet for large video files it would be well worth the CLI effort.