The scalable/supportable way to have a fixed IP address is to have a DHCP reserved address configured for you by network administrator.
They will need the physical mac (media access control) not “Apple Mac” address of your device and input into their DHCP server configuration.
With a DHCP reserved address, your iPad with work properly on both that network and any other public Wi-Fi network you may use occasionally.
With a manual fully static address (which sounds like what you have tried), you need the exact subnet mask and router address to manually configure yourself. Your network might be using ‘supernetting’ or CIDR routing so the default /24 mask of 255.255.255.0 is probably not correct.
If you use a fully static IP, you must remember to delete it when using another Wi-Fi network and then re-set it back when returning to your primary network - thus a server-controlled DCHP reserved address is a much better “set it and forget it” solution.
Also, you didn’t say if you were on a private isolated network or a network that has Internet connectivity.
For DNS settings, the easiest way to manually configure them is to use the absolute dotted.decimal notation (such as 18.104.22.168) which avoids a potential infinite DNS-lookup failure.
22.214.171.124 and 126.96.36.199 are the global free Google DNS servers. Ignoring security or privacy issues, when having trouble getting connected to a network, manually setting DNS to a well-known public DNS server eliminates one of the potential issues. Once working, you can substitute your own/local DNS servers if desired.