@parosen 

How about checking with this instruction? https://www.tp-link.com/us/support/faq/3043/

@John1234 

Thank you very much for you answer

Actually the link you posted is one of the documentation I was referring to.

According to this document, Status info should be provided in odin .1.3.6.1.2.1.2.2.1.8 tree.

Using smnpwalk in my router the tree returns this:

.1.3.6.1.2.1.2.2.1.8.1,Integer,1
.1.3.6.1.2.1.2.2.1.8.2,Integer,2
.1.3.6.1.2.1.2.2.1.8.3,Integer,2
.1.3.6.1.2.1.2.2.1.8.4,Integer,2
.1.3.6.1.2.1.2.2.1.8.5,Integer,2
.1.3.6.1.2.1.2.2.1.8.9,Integer,1
.1.3.6.1.2.1.2.2.1.8.11,Integer,1

I can tell 9 and 11 are the WANs, because if I look in the whole odin tree that is returning, I can find their mac addresses 

.1.3.6.1.2.1.1.9.1.3.1,OctetString,The MIB module for managing IP and ICMP implementations
.1.3.6.1.2.1.1.9.1.3.2,OctetString,The MIB module for SNMPv2 entities
.1.3.6.1.2.1.1.9.1.3.3,OctetString,The MIB module for managing TCP implementations
.1.3.6.1.2.1.1.9.1.3.4,OctetString,The MIB module for managing UDP implementations
.1.3.6.1.2.1.1.9.1.3.5,OctetString,View-based Access Control Model for SNMP.
.1.3.6.1.2.1.1.9.1.3.6,OctetString,The SNMP Management Architecture MIB.
.1.3.6.1.2.1.1.9.1.3.7,OctetString,The MIB for Message Processing and Dispatching.
.1.3.6.1.2.1.1.9.1.3.8,OctetString,The management information definitions for the SNMP User-based Security Model.
.1.3.6.1.2.1.1.9.1.3.9,OctetString,RFC 2667 TUNNEL-MIB implementation for Linux 2.2.x kernels.

.1.3.6.1.2.1.2.2.1.6.1,OctetString,
.1.3.6.1.2.1.2.2.1.6.2,OctetString,
.1.3.6.1.2.1.2.2.1.6.3,OctetString,
.1.3.6.1.2.1.2.2.1.6.4,OctetString,
.1.3.6.1.2.1.2.2.1.6.5,OctetString,
.1.3.6.1.2.1.2.2.1.6.9,OctetString,  C0 C9 E3 DA 07 C4
.1.3.6.1.2.1.2.2.1.6.11,OctetString,  C0 C9 E3 DA 07 C3
 

if there is a  link down, .1.3.6.1.2.1.2.2.1.8.9 or .1.3.6.1.2.1.2.2.1.8.11, depending on which one is down, should be returning something different to 1

As I tried to configured this with the last firmware already, I don't if this is a problem introduced by the last firmware version, or it was always like this or I'm doing something wrong