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 18.104.22.168 and 22.214.171.124 a lot now.
My wife has a new Acer Icona One & tablet. Has 16 Gb. and she has installed nothing but Facebook. That's the only thing she uses it for is scrolling FB. Problem is , it stops frequently, then starts, then closes, etc. Seems like the problem is that it keeps dropping wifi. Basically it's used in the next room from the modem. We have a desk top and two cell phones and have no issues with them. Any ideas?