Issue with videos, very specific

I've always used Firefox, always updated. Recently, some videos on YouTube don't play, but only a few... and videos sent via WhatsApp Web too, they don't play. But this only happens when I use a specific Wi-Fi network. On all the others, everything works 100%. The place where I use this specific Wi-Fi network is where I work, at home it works normally. Any idea how to solve this? On all the other browsers everything works normally. Sometimes the videos that don't play...if I close the tab and open a new one, they play...