Thanks for reaching out. We'd love to help.
A few questions: when did the issue start? What country are you from? What radio stations are you trying to play? What troubleshooting steps have you tried so far?
Reboot your Google Nest Hub by unplugging and plugging it back in for a minute. You may also try to factory reset it and set it up like a new device. View this link for the steps.
Let me know how it goes.
Thanks for providing the information. Please note that we can only guarantee the full functionality of the Google Home/Nest speakers and displays to those countries where it was officially released and supported. Unfortunately, Portugal is not in the lists. Also, occasionally, a station may become unavailable at the broadcaster's request due to geographical or other restrictions. In most cases, TuneIn may attempt to redirect you to a similar station to provide relevant content.
If you've tried all the steps like rebooting and resetting your speaker, the best thing to do is to send feedback on your device. You can also try to change the Assistant language to EN_US and see if that makes any difference. Please note that this is just a workaround and no guarantee that it will work.
Let us know if you have additional questions, otherwise, I'll lock the thread after 24 hours.