So you''re using ip addresses not names. Even so that's a long wait.
If I use Connect To Server in Finder with the direct smb:// url to the IP of the server then wait about 2 mins the login box appears. I enter my login details as I would log into the linux box and then press connect. After about 5-8 mins it will error out.
Did you add the linux user to the samba password database:
And do the Linux permissions allow access to that shared folder by that user:
sudo smbpasswd -a user-name
EDIT: There was an odd bug some time ago about smb://ip-address. I never experienced it myself but the solution was to use cifs://ip-address instead. It may have been fixed by now so this may no longer be relevant.