For some reason, I ended up with this SOHO router. It has been deployed by one of the biggest ISPs in Spain for some time (I've no idea if it's still being distributed). I bought it in a second hand store to configure it with my current ISP, and it ended up being a good device.
The firmware it had when I got it was quite bad, lots of configuration parameters missing, slow interface, ... So I surfed the Internet for a better solution.
At some point of my journey, I found this website (http://www.speedtouch.com.br/td5130.htm), which seems to be the Brazilian Technicolor site, and offers a firmware download. This firmware is for the Brazilian GVT ISP.
TD5130 V2.05.C17GVD (GVT) (SHA1 904d8d9153b3e0b90165e973cd5a29553a6933cc).
In this case the panel is "as is", with all advanced options, which is a much better solution for my use case.
At this point, I wanted to know the mechanisms of the router under the hood, so I started extracting the filesystem. It is an embedded Linux system, MIPS architecture.
I didn't find nasty tricks (yet?), but one thing caught my attention. There is a specific configuration panel that is not present in the regular panel tabs or buttons. This panel contains the TR069 settings, which is a protocol that basically gives the ISP control over your router to perform diagnostics, upgrade or change your firmware, and monitor your device.
This is what they use when you have a problem and call the support center, but I guess not all people want this protocol enabled (which is the default).
Anyway, to access this setting you have to login in your router and directly open the url http://192.168.1.1/tools/tools_tr069_setting.shtml
There you can enable/disable the protocol, change and see settings, ...
It's needless to say that I'm not responsible of your actions, so if you completely mess it up, and the router doesn't work anymore, deal with it.
Regarding the device it's quite simple, the configuration gives you a lot of possibilities, and I can't complain about the overall performance.