This sounds like a defective tablet or another Facebook issue. Yesterday Facebook was down and created a lot of posts across the web about that and "My PC drops WiFi." When asked how they knew they responded they couldn't get to Facebook.

There is another reason which is the DNS used so while I don't expect everyone to know this, here is an article about changing to a better DNS: https://www.howtogeek.com/167533/the-ultimate-guide-to-changing-your-dns-server/

I'm using 8.8.8.8 and 4.2.2.1 a lot now.