If it is working fine elsewhere, on all other WiFi connections, then it isn't the tablet. It is, however, your modem/router or your ISP.
I know you said the other devices work fine on it, however that is really common. All it takes is one device to be more 'sensitive' (so to speak) and you will get issues.
First try seeing if it only happens when you are in certain areas of your home. If that is the case, you may need to change where your modem/router is placed to get constant good connections.
Should that not work, try rebooting your modem/router and see if that resolves it.
If, again, the problem still continues, then I would monitor your internet connection. Check the speed, and other info multiple times over a period of time...