[LG V30 Questions & Answers] enginesong:
Issue (TL;DR):

Previously working fine. Mistakenly changed USB connection option to "charge only/always". Hassle to change it back to MTP but did. Now unstable connection when attempting file transfer via USB to Windows 7 PC. Known good cables.

Phone: LG-US998 (unlocked LC V30)

Android: 7.1.2 (stock)

Security patch: September 1, 2017 (stock)

Kernel: 4.4.63 (stock)

Build: N2G47H (stock)

Software: US99810b (stock)

Cables: AUKEY USB C Cable 3.0 (I have 3 of them).

PC's: Windows 7 and Linux Mint 18.something/cinammon. Direct USB 3.0 ports, no hubs.

Issue in detail:

1.) Everything was working fine. Good connections and successful file transfers between phone and multiple PCs and cables.

2.) Was connected via Aukey USB3.0 cable1 to Windows 10 PC. Just wanted to charge, didn't want to have file transfer active.

3.) Selected "charging only" option and "always" by mistake. This seems to be "the change" that messed everything up.

4.) Finally needed to transfer files over the weekend. Plugged Aukey cable2 into Linux Mint PC but did not get a chime or a pop-up window like normal. Looking at DISKS and phone is not visible.

5.) Remembered that I had made this change and went to go change it back. Found out that there are no options in the settings menus to do this. This seems like a bug.

6.) Tried to select a different option with the drop down after connecting. No options available even when tapping on the notification that normally brings up the USB connection options. This seems like a bug, too. Or maybe an oversight.

7.) Unlocked developer options to get to USB connection menu (this seems like overkill to change this setting back). Found "Select USB Configuration" under "Networking". Changed from "charging only" to "MTP".

8.) Disconnected USB. Reconnected USB. Didn't work. Phone still not found. Verified with Aukey cable2.

9.) Went back to developer options, turned on USB debugging. Repeated step 8, same result.

10.) Went back to developer options, revoked USB debugging authorizations. Repeated step 8, same result.

11.) Tried plugging into a different port on the PC(Linux Mint). This worked. Which seems strange. Just used next port over on motherboard.

12.) Thought strange but ok, works, don't care. Verified with Aukey cable2.

13.) Attempt file transfer on Windows 7 PC today. Kinda works, but isn't stable. Used Aukey cable 1.

14.) Plug phone in, pop up window that shows internal storage and SD card like normal. Think cool, still works. Delve into deeper subdirectories of SD card, find the one I need, start copying, phone disconnects. WTF.

15.) Try again, same thing. Never had this issue before.

16.) Works better if I go really slow (select SD, wait 10 sec, select DCIM, wait 10 sec, select Camera, wait 10 sec, select target folder, wait 10 sec, copy contents [about 500 pictures], paste to windows destination). However, the connection will still drop randomly in the middle of file transfer. Error message on PC is "The device is not connected".

17.) When this happens, the phone shows no connection, then automatically reconnects. Then get the pop up on the phone showing usb connection options like normal and windows pops up with the root file folder (internal and SD) like normal. It is behaving like I am disconnecting the USB cable.

18.) Repeat step 16, same results.

19.) Tried different USB ports. Same issue.

20.) Tried debugging on/off, oem on/off, revoke authorization yes/no, select charge only then back to MTP. Same results.

Seems like something broke when selecting USB charging only/always the first time. So I would recommend against that based on what I experience. Now, hopefully someone can help point me in a direction that helps solve this for me.

Options:

1.) Prefer not to go nuclear and factory reset. But I guess that would probably work.

2.) Is the bootloader unlocked for this phone? I would like to make an image for backup regardless, but this would make me feel a lot better about a factory reset.

3.) OTA available for US99810c. I could apply that but not sure if that would fix it as I haven't seen a good write up of all the changes from b to c. Also, would this prevent me from bootloader/root? I am not up to date on this phone but have done that kind of thing before (OG droid, galaxy S3).

4.) Don't want to unmount and remove SD card to file tranfer, that's just archaic.

Thanks in advance.