I have network with new central server in main office and legacy branch servers. Central server is OES2 with eDir. SAMBA is connected to eDir through LDAP and use it as data storage. All computer accounts and users are registered in eDir. Samba services provide simple Windows domain. Legacy branch servers are windows based and some are gentoo linux based. Samba is updated to latest available stable version. Windows machines join domain without any problems and work normally. Problem is with samba on branch server with linux.
On a branch server i have configured samba to use central server as password source. Branch servers do not have direct access to eDir and they are not DC. On branch server I type:
net rpc join -Uadministrator%p@ssw0rd and after few seconds I get response:
Joined domain COMPANYDOMAIN.
Users now can get all data from server, net use command is working properly and everything is fine.
Problem appear exactly after ONE WEEK!!! User see it as inability to connect to mapped disk. Windows throw an authentication window and does not accept correct username and password combination. Samba service restart on branch server does not help. I must write net rpc join command again and after that everything appear to be fine (for one week again). It seems, that
branch server can not get password from central server. Maybe there is something like ticket with validity period?

Can somebody explain, why samba from branch server can get authentication from central server only one week? OK, i understand, that I can put in crontab to perform this net rpc join at monday at 7 o'clock, but anyway this is a kind of misconfiguration or a bug.

Thank You!