Problems connecting PPPoE in a multi WAN system

I'm currently running into a problem after switching from DSL with modem to a fiber connection without modem. ClearOS is connected directly to the NT box (Fiber to Cat interface)

What I did so far:
Used a un-configured NIC and added a VLAN on it. - Role External - Type DHCP - VLAN ID 6
Then eddited the VLAN addapter to PPPoE - Role External - Connection type PPPoE - Username (mac@internet) - Password (provided by ISP) -MTU 1500
After update the VLAN addapter is gone and settings in ifcfg-enp4s0.6 changed and ifcfg-ppp0 is created.
At this point there is no connection. I found this topic and added a additional VLAN Same as first time, this corrected the file ifcfg-enp4s0.6. At this point no connection at all.

Then I started over with the information i found here, Changed Iface.php and added a firewall rule as described.

From there I removed everything and started over again. Now I have a very unstable connection. With this in the logfile messages:

Jan 12 15:53:48 gateway pppoe-connect: PPPoE connection lost; attempting re-connection.
Jan 12 15:53:53 gateway pppd[14578]: Plugin /usr/lib64/pppd/2.4.5/rp-pppoe.so loaded.
Jan 12 15:53:53 gateway pppd[14578]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.5
Jan 12 15:53:53 gateway pppd[14578]: pppd 2.4.5 started by root, uid 0
Jan 12 15:53:53 gateway systemd-sysctl: Line is not an assignment in file '/etc/sysctl.d/99-sysctl.conf': (null)
Jan 12 15:53:53 gateway pppd[14578]: PPP session is 25606
Jan 12 15:53:53 gateway systemd-sysctl: Line is not an assignment in file '/etc/sysctl.conf': (null)
Jan 12 15:53:53 gateway pppd[14578]: Connected to 00:00:00:10:2f:30 via interface enp4s0.6
Jan 12 15:53:53 gateway pppd[14578]: Using interface ppp0
Jan 12 15:53:53 gateway pppd[14578]: Connect: ppp0 <--> enp4s0.6
Jan 12 15:53:53 gateway pppd[14578]: Remote message: Authentication success,Welcome!
Jan 12 15:53:53 gateway pppd[14578]: PAP authentication succeeded
Jan 12 15:53:53 gateway pppd[14578]: peer from calling number 00:00:00:10:2F:30 authorized
Jan 12 15:53:53 gateway pppd[14578]: Unsupported protocol 'IPv6 Control Protocol' (0x8057) received
Jan 12 15:53:53 gateway pppd[14578]: local IP address 81.205.120.xx
Jan 12 15:53:53 gateway pppd[14578]: remote IP address 195.190.228.xx
Jan 12 15:53:53 gateway pppd[14578]: LCP terminated by peer
Jan 12 15:53:53 gateway pppd[14578]: Connect time 0.0 minutes.
Jan 12 15:53:53 gateway pppd[14578]: Sent 0 bytes, received 0 bytes.
Jan 12 15:53:53 gateway pppd[14578]: Modem hangup
Jan 12 15:53:53 gateway pppd[14578]: Connection terminated.
Jan 12 15:53:53 gateway pppd[14578]: Failed to disconnect PPPoE socket: 114 Operation already in progress
Jan 12 15:53:54 gateway systemd: firewall.service: main process exited, code=killed, status=15/TERM
Jan 12 15:53:54 gateway systemd: Unit firewall.service entered failed state.
Jan 12 15:53:54 gateway systemd: firewall.service failed.
Jan 12 15:53:57 gateway clearsyncd[1441]: System Events: Socket hang-up: 30
Jan 12 15:53:58 gateway pppd[14578]: Exit.

This keeps repeating its self. Is there anyone who can help to diagnose this and find a solution. It also looks as if my firewall stopped working.