Find My iPad can only be deactivated from the device that it protects. Without an internet connection, if enabled, this protective measure cannot be disabled.
Are you having difficulties connecting to your WiFi network - or are you connected to WiFi (the icon shows a good WiFi signal) but have difficulties connecting to the internet? These are two entirely different issues.
If your issue is actually connecting to WiFi:
If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support
You may also need to check your Router’s WiFi settings:
Recommended settings for Wi-Fi routers and access points - Apple Support
If you can connect to WiFi, but cannot connect to the internet, the problem is unlikely to be a WiFi issue, but more likely a problem obtaining a valid IP Address for your iPad from your WiFi network.
If you have a VPN App or profiles installed, or a security App such as Norton, these may be interfering with DHCP - and may need to be temporarily disabled.
DHCP is frequently used to automatically obtain an IP Address from your WiFi Router. Until your iPad has a valid IP Address to connect to your network, you will not have an internet connection. Disabling or removing VPN and/or the offending security App should allow DHCP to operate normally - allowing connection to your network and the internet.
If this resolves your issue, the VPN and/or security App can be reinstated after the connectivity problem has been resolved.
An alternative approach to restoring a working network connection is to manually set a static IP and Router in your iPad settings - that is appropriate for your WiFi network.