Hi Victor,
2 recommendation
1-check resolution betwenn 2 server.
2- did you created a admin user on Dp GUI:
on oracle server run:
su – oracle
$cd $ORACLE_HOME
$ll
$ ll
total 128
drwxr-x--- 4 oracle oinstall 1024 Sep 30 15:59 OPatch
drwxr-x--- 3 oracle oinstall 96 Sep 30 16:15 admin
drwxr-x--- 7 oracle oinstall 96 Sep 30 15:55 assistants
on this case user oracle , domaind oinstall.
hope this help