Hello there is something that is driving me crazy, hope some of you expert can help me to understand.

 

I have a ISP modem/router that is a bit limited in functionalities as typical, it takes the VDSL line and then I connect one LAN port to the WAN port of the router TL-R605, then the LAN port of this router is connected to the switch and so to the other clients.

 

The connection of my provider is the following:

• Retransmission (ITU-T G.998.4)
• Vectoring ( ITU-T G.993.5)
• SRA (ITU-T G.993.2)

• USERNAME: xxxxxxx
• PASSWORD: xxxxxxx
• PROTOCOL: PPPoE Routed (defined as RFC 2516) 
• ENCAPSULATION: PTM
• NAT: active 
• VLAN: 835

 

I wanted to use the ISP router as a modem only but there is no this option, so what I have done is to disable: NAT, DHCP and putted firewall at minimum.

The TL-R605 has this configuration:

 

With this setup everything is ok in the way that clients connected to the TL-R605 can go on WAN and LAN.

Even if I leave NAT and DHCP on in the ISP router everything still works, but my intention was to try to have it working as much as possible as a modem only.

 

As you can see below thge PPPoE connection of the ISP router is still active and gets a public IP: 79.xx.xx.169

If I go on a computer connected to the second router and check what is my public IP i get a different one: 79.xx.xx.208

Now they appear very similar but some other times they are completely different IP.

Here my questions:

 

1) is my setup correct ? especially the one with PPPoE disabled on ISP router.

 

2) I was thinking that the ISP router was getting a public IP and transferring it to the second router, should not be like this ? Apparently not, so but why a second public IP is generated for the second router ? Consider that both addresses are pingable, so they are effectively existing and true addresses.

Should it work in this way ?

 

3) I tried to disable PPPoE on ISP router, and everything still works, then I don't see anymore the public IP of the first router of course, do you think this is the correct setup ?

But in any case the DynDNS service works only is settled in the ISP router, it doesn't work in the second even with PPPoE of first router disabled.

Do you have an idea of why ?

 

4) With PPPoE disabled on the ISP router (and also NAT, DHCP) should not be like modem only ?

 

5) my problem is that if the second router cannot update the DynDNS I cannot use it for things like OpenVPN or other stuff that requires it

 

6) if I enable VLAN 835 as requested by provider then the TL-R605 fails in the connection even if on the first router I have PPPoE enabled or disabled ? Do you have an idea of why ? In other words it works properly without VLAN enabled that is a required parameter.

 

Thanks in advance for your help