Hi people, how are you?
I write this to let you know that you can close this support ticket. (I write this to No-IP support team)
The whole problem, I think it was related from the beginning with the Google Chrome cache, because yesterday morning (I'm in Brazil), I completely reinstalled OpenWRT on my router so that I could avoid any issues related to possible corrupted files, but I didn't install Luci, which is her GUI, so I set up everything I need via command lines and configuration files, where everything worked perfectly and so far ...
Thank you so much for your support so far.
Strong hug!