Sin conexión a internet ISP backup

Hello,

Yes, I plan to update the version later.

I also tried enabling the specific NAT rule for ether4 marked #0, and it didn't work either. The result was exactly the same: I could access the internet from the Mikrotik, but not from the internal network.

Flags: X - disabled, I - invalid, D - dynamic 
 0    chain=srcnat action=masquerade out-interface=ether4 log=no log-prefix="" 

 1    ;;; defconf: masquerade
      chain=srcnat action=masquerade out-interface-list=WAN log=no log-prefix="" ipsec-policy=out,none 

 2    ;;; srnat-sslvpn
      chain=srcnat action=accept src-address=a.b.c.0/24 dst-address=d.e.1.f.0/24 log=no log-prefix="" 
[admin@RouterOS] >  

It would be a great help if anyone could give me some other ideas. I can't find the problem. I've even considered that it might be related to the PPPoE configuration, but this is really strange what's happening with the Mikrotik.