@Kevin_Z 

First of all thanks for answering me. Secondly sorry for my Google translator english.

The Archer C80 is the main router (192.168.1.1) and I have a fixed IP on the network (PPPoe).

I use Windows Explorer itself and access the CloudBox folders always through the external IP. Everything normal, working perfect.

The door release is as follows:
External: 8221 (my provider blocks 21)
Internal: 21   (CloudBox)
IP: 192.168.1.2
TCP-UDP (ALL)

In all the other routers from TP-LINK, Xiaomi, Asus and Intelbras that I've always used, I never had a problem, but on this one, it's like having an access block. I enter the CloudBox password when asked by Explorer, there is a delay and returns expired time. In the others mentioned above, it already shows the folders immediately.

Already tried to downgrade the firmware, but it is the same.

At the moment Archer C80 is saved, because I can't leave FTP without working. I depend on it for customer backup.

I thank the attention.

@Kevin_Z 

OK no problems!

WAN IP: 187.17.***.*** (FIXED)

LAN IP: 192.168.1.1

DHCP: 192.168.1.11 - 99.

Open door:
External: 8221
Internal: 21
IP: 192.168.1.2

There are no other routers on the network, I just mentioned other brands and models of TP-LINK itself that work when I change the router.

It's a simple home network.

Access through the ip of the local network he accesses normal.
(\\192.168.1.2)

Security camera ports and other UPNP services all work.

I suspect it might be a firmware firewall rule, but I have no way of knowing.

How do I maintain email support, just answer what you sent me?

What information do you need?