Map multiple network drives with different users

[BBNifu]

Hi all!
So up until now I worked with a single shared folder and mapped it on my Win10 machine as a network drive. I created a user on the NAS and granted permissions to that folder. Works like a charm. (I got the credentials box when mapping the drive, put the user and PW and it just worked).
I now created another shared folder that I want to map with different credentials. I created a new user and when I try putting the credentials for that one while mapping the network drive, it just doesn't work. The only thing that works for me is unticking the "use different credentials" box... which means that the same old user is used for this share. Also when I remove the access rights for the first user from my new share I cannot access it at all. Another thing that sounds strange to me: even when using the credentials for the first user, it does not work. It only world when I put no credentials whatsoever.
Why do I even need this? My backup software cannot handle mapped drives and when connecting to a network share it asks for credentials. None of them work - not even admin.

Both users have RW access to both shares.
Not using AD auth or anything.
Password(s) listed as always valid.
Also created a group for both users, granted permission to the group. Did not help, just made me lose access to all shares, so I decided to ditch the group thing.

Any suggestions?

[jaysona]

Basic windows networking.

You can connect using only one username/password from the same workstation.

[dolbyman]

This app costs money .. should we see this as an advances ploy to pluck an app (two fist time posters) or let it slide ?

[OneCD]

That's up-to-you @dm.

Personally, I ban any FTPs (first-time-posters) who "advertise" paid applications/services.

[dolbyman]

Apparently it's the developer of this app ... posted a bunch of times in several forums recently .. sneaky

Ban applied