I skipped the many comments here.
I am using FTP or SFTP in my local network.
You can check FTP if it is faster than SMB.
I do not know why do you need SMB more than FTP.
FTP is the largest standard protocol for file transfer. Every OS supports it.
I ran it on the main drive (EXT4 formatted)
Writing 1GiB
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 2.10403 s, 510 MB/s
Clearing Cache
vm.drop_caches = 3
Reading 1 GiB
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 2.31819 s, 463 MB/s
Removed 1Gib tempfile
I wasn’t able to do it on the other disk as for some reason it wouldn’t let me access it through terminal (permission denied). Had a look at it in KDE Partition Manager and had a locked doovy on that partition.
But read/writes speeds are about right for this drive.
To tell the truth, I hadn’t really thought about FTP. Last time I used FTP was 20 years ago when I was doing web pages and it was the ONLY way of getting files onto the server. And it was slow and tedious then. I figured it still hadn’t changed much!
Anyway, gave it a run in Nemo from the File/Connect to Server option to the QNAP and you’re right. Smashes the file over at about 115MB/s!
I’ll have to look up whether FTPs enabled on the other smaller Seagate and WD servers I have as it wouldn’t let me connect via FTP to them. They’re not as important as they’re used for backups and I can just mount them in the FSTAB file like I have been if need be.
Are you auto mounting your ftp connections?
I looked up the CurlFtpFS wiki and to include it in FSTAB it says
You can add this line to /etc/fstab to mount automatically.
curlftpfs#USER:PASSWORD@ftp.example.com /mnt/exampleorg fuse auto,user,uid=1000,allow_other,_netdev 0 0
Tip: You can use codepage="string" when having problems with non-US English characters on servers that do not support UTF8, e.g. codepage="iso8859-1"
To prevent the password to be shown in the process list, create a .netrc file in the home directory of the user running curlftpfs and chmod 600 with the following content:
machine ftp.example.com
login username
password mypassword
I gather the .netrc file has to be in the immediate /home directory of the user running ftp. And how do you pass that file through the CurlFtpFS command? Didn’t seem to show any options in the wiki. Or it just checks the home directory for a file name .netrc when connecting via ftp?
And does the .netrc file need to be named something specific to the ftp connection?
Thanks for the great tip!
And there is also sshfs. This is what i use. When ssh works, sshfs will work also 
Thanks for the suggestion.
I gave it a try, but seems to be a bit slower than FTP for my system. But there seems to be a few different ways to achieve the same result (which can only be a good thing)
I’m impressed:
Writing 1GiB
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.422196 s, 2.5 GB/s
Clearing Cache
vm.drop_caches = 3
Reading 1 GiB
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.652759 s, 1.6 GB/s
Removed 1Gib tempfile
You are using PCIE 3.gen NVME SSD. right?
If yes, no wonder. 
Indeed! 
Thanks everyone who tried to help out with this problem. While the original question wasn’t solved, at least there’s a work around. And I learned a bit on the journey.
I think the SOLUTION is - use anything but Samba with File Managers in Manjaro 
. It works OK if you implement it in an FSTAB file (about 75% speed), not so much just connecting through the File Manager (20% speed). Dolphin has it’s own issues as well with Samba (even when implementing with an FSTAB file it’s only 60% speed).
If you’re going to use a File Manager to connect with a server, just use FTP - It seems to be the go. I found both Nemo and Dolphin copy at maximum speed with FTP just connecting through their interface.
I guess we’ll have to chalk this one up to an issue with the way Samba is implemented in the file managers in Manjaro perhaps? At least I’m able to transfer large files fast now in Linux.