The merge process could not connect to the Publisher ' '. Check to ensure that the server is running. ( I have 2 servers with 2 kinds of replications between them.
One is Transactional and the other is merge.

The Transactional replication is working fine but in the merge replication, I'm getting error messages.

Error messages:


  The merge process could not connect to the Publisher ' '. Check to
  ensure that the server is running. (Source: MSSQL_REPL, Error number:
  MSSQL_REPL-2147198719) Get help: http://help/MSSQL_REPL-2147198719 The
  process could not connect to Publisher ' '. (Source: MSSQL_REPL, Error
  number: MSSQL_REPL20084) Get help: http://help/MSSQL_REPL20084 Login
  failed. The login is from an untrusted domain and cannot be used with
  Windows authentication. (Source: MSSQLServer, Error number: 18452) Get
  help: http://help/18452


Two weeks ago everything was working fine (we didn't change anything and they didn't change as well).

I've read and check that the user is db_owner.
Telnet is open (and the transactional replication is working) so there are not any network problems.
I deleted and recreated both replications.

when I'm looking at the publisher server events log I see the error


  SSPI handshake failed with error code 0x80090301, state 14 while
  establishing a connection with integrated security; the connection has
  been closed. Reason: AcceptSecurityContext failed. The Windows error
  code indicates the cause of failure.


Any ideas?
The error message is stated plainly:


  Login failed. The login is from an untrusted domain and cannot be used with Windows authentication


Try logging in to your Publisher as the replication agent account running on the subscriber (connecting from the subscriber through SSMS). There could have been changes to domain trusts, changes to domain membership, broken SPNs etc that could be causing this.

Validate your domains have a trust between them, your SPNs are configured correctly and that your replication accounts can actually log in to each instance. Also, double check that the accounts themselves are not disabled and\or have expired passwords.