Model :

Hardware Version : Not Clear

Firmware Version :

ISP :

Hello,

I have a problem that most of you will consider really simple. But since i´m starting in the world of networks i need to ask.

I have a Router Tl-er5120 with the more simple configuration, with 1 wan port and 4 lan ports, everything in the router works ok.
In one of the lan ports I have a PC (PC A).
In other of the lan ports of the router I have a smart switch connected Tl-sg2210p
In one of the ports of the switch I have another PC (PC B).

No VLAN or anything else was setup so far.

The problem is that from PC A I can ping Router, Switch and PC B.
From Router I can ping the Switch and both PCs.
From PC B I can ping PC A and Switch, but cant reach the Router.
And from the Switch I can´t Ping the Router either.

Anybody could tell me wath configuration I am missing?

I have readed that maybe the VLAN of the smart switch have no permition over the TRUNK, but I didn´t configurate a TRUNK yet.

Thanks in advance.