I'm not sure if this is the right forum for this question.
It's not a network problem but more of a samba issue.

I'm running Linux Mint 19.2 XFCE on a desktop PC.
The issue I'm having is when I try to move or copy a large file > 500K from the PC to a USB-Disk that's set up as a samba drive on my Technicolor EPC3940ADL router (supplied by my ISP), I get this message:
"there was an error copying the file into smb://iinetcable-smb/storage/USB-Drive/ -- Network dropped connection on reset."
Moving any file from the Network Share USB drive to the PC presents no problems.

I had no problem on the same PC running Linux Mint 17.3 or from another Linux PC running Linux Mint 18.3.

I have tried a couple of different distributions using "live CDs" with the same result (same computer and other computers). These other distributions are based on Ubuntu 18.04.
I believe something has changed (samba protocols?) in 18.04 that has bought about my problem.

I cannot change anything in the router and the only option available to access the USB-Drive is samba.

Any help appreciated.
John

It does look like a version problem. SMB version 1 has a bunch of security problems, Microsoft has dropped support and most mainstream distributions default to version 2+. Since you posted smb:// I assume your connecting to your router using the file browser versus mounting via the command line. I don't know if the file browser built in samba client has changed too will have to check.

As a workaround mount the share using the command line by specifying vers=1.0

https://forums.linuxmint.com/viewtopic.php?t=276519

Thanks for the link michaelk.
It was useful in pointing me towards understanding my problem.

These are the steps I took to solve my problem.
For reference, the router IP is 192.168.10.1 and the Samba share name is iinetcable-smb

Firstly I created a share point:

sudo mkdir /mnt/router-share

and added the following line to /etc/fstab

//192.168.10.1/storage /mnt/router-share cifs guest,vers=1.0

ran the command:-

sudo mount -a

and it came back with:- "mount error(2): No such file or directory
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)"

I then did some digging into mount.cif so that I could try mounting the router share from the command line instead of constantly editing /etc/fstab.

sudo mount -t cifs -o guest,vers=1.0 //192.168.10.1/storage /mnt/router-share

This returned the same error message.

I also tried substituting the samba name for the IP address.

sudo mount -t cifs -o guest //iinetcable-smb/storage /mnt/router-share

The response was:- "mount error: could not resolve address for iinetcable-smb: Unknown error"

Was this an address issue or maybe I had the wrong share directory, I ran the command:-

smbclient -N -L 192.168.10.1

It returned the error:- Connection to 192.168.10.1 failed (Error NT_STATUS_IO_TIMEOUT)

However, if I run the command:-

smbclient -N -L //iinetcable-smb

It returns with all the sharenames, servers and workgroups.

Very confused.
After more digging and Googling, I came across nmblookup

nmblookup iinetcable-smb

It returned the result:- 192.168.10.12 iinetcable-smb<00>

The IP address is different to the router address!

Changing the IP in the mount command used earlier:-

sudo mount -t cifs -o guest,vers=1.0 //192.168.10.12/storage /mnt/router-share/

Mounted the router USB-Share without error and I was able to copy large files to it without problem.
I amended the IP for the router in /etc/fstab and everything works OK.

I tried other SMB version numbers (2.0,3.0) with the command line mount command but they returned the same "mount error(2): No such file or directory" response.

I'll add SOLVED to this thread as this seems to be the best solution to my problem.
I think eventually I'll remove the /etc/fstab entry and set up a custom action in the File Manager to run a small script to mount the router share as needed.

Regards,
John

You can also use autofs or systemd automount feature to only mount the share when you access its mount point.

I just tried transferring a 681MB file from my router share to my Mint 19.2 VM and back and was successful. I need to try a bigger file.

Thank you again michaelk.

Googled "systemd automount" and clicked on the first link: https://forums.linuxmint.com/viewtop...8aa268723d2ae6

The answer supplied by altair4 explained exactly what I want.

So I changed the mount point to my home directory and re-edited /etc/fstab to:-

//192.168.10.12/storage /home/john/router-share cifs rw,guest,vers=1.0,iocharset=utf8,_netdev,noperm,noauto,user 0 0

A mount icon appeared in the side panel of the File Manager. Clicked on it and the share directory opened up with full access to all the files.
Perfect.

Regards,
John