@terziyski  

Unfortunately, things like opening ports or activating DMZ (the general fixes that exist throughout the internet) do not solve anything for me. I still have the problem of a "symmetric NAT" and there is no option on the router's local website to modify the NAT. That's why I was wondering if updating the firmware would somehow make that option appear there.

  @JoseManuel22 

Hi,

Most routers made for use in home networks have no NAT type selection. So I don't think the NAT of your TL-WR740N is causing the problem.

If port forwarding or DMZ don't solve the problems you are having with that online video game, then there is a good chance your Internet Service Provider has another NAT on their side (referred to as "CG-NAT"). 

Have you already checked whether the Internet connection of your router has been assigned a public IPv4 address by your ISP?

In case your router's IP address is a private IPv4 address, then there must be another NAT beside the one inside the TL-WR740N somewhere.

 @woozle Thank you very much for the answers.

When I say that the problem is the NAT, it is because the game page tells me so. That's why I insist on that problem. I am attaching a screenshot so you can see it.

About IPv4, I don't really know what you mean by that. How can I check that?

  @terziyski 

Sorry for responding so late and thanks for the response. I already went to the page and saw that there is indeed an IP address there, but I don't understand what exactly I should do with that information. Excuse my ignorance, I don't understand almost any of this. 

I just want to fix this and I can't.

  @terziyski 

Apparently I have an IP there between one of those ranges.

About port-forwarding, I have no idea how to do it correctly or I don't know if it even works. I tried it a few weeks ago. It asks for a lot of data that I don't even understand and when I tried to put in what the internet was telling me I ended up with a slow connection and I had to deactivate it and it never solved my problem anyway. Is there any way to do it correctly?

  @JoseManuel22 

Two things.

1) If you find port forwarding too complicated, then just use the DMZ feature. It will just forward everything. All you need to do is enter the IP address of the computer you use to play the game.

2) If your WAN IP address falls within one of the four address ranges that terziyski mentioned earlier, then there is another (symmetric) NAT elsewhere. In this case nothing you do on the TL-WR741ND can solve this problem, not port forwarding and not DMZ. Even replacing the TL-WR741ND with another router would not help.

By the way. Where does the cable you've plugged into the blue Ethernet port of the TL-WR741ND come from? Does it just go into a wall? What type of broadband Internet have you got? Fiber, cable, DSL?

  @woozle 

Thanks for the reply.

1. About the DMZ, the IP that I have to set is the LAN IP, right? If I'm right, I already did it and it doesn't work. If not, forgive my ignorance, I don't really know what I'm doing. Another thing I noticed is that it asks me to have the "DHCP client function" disabled, but I have it active. I don't really know if I should remove it since it came from the factory and I don't know what repercussions it has. Anyway, if it's not that bad, I can remove it. I would like you to confirm if it has anything to do with it.

2. I use fiber. The cable comes from a device that, at the same time, is connected on the street.

By the way, my router is not a TL-WR741ND but a TL-WR740N, I put the first one in the post because I did not find the second one in the available options when creating the post. Sorry for the confusion.