While connecting to WiFi very often we get Limited Connectivity, Can anyone tell me the root cause of this issue and the resolution please?

Check first your windows is updated or not. if not please update is first.

since you tried all of the basics troubleshooting that you mentioned,  i suppose the root cause of this problem is due to your ISP or your internet gateway, try to restart your router, if you made sure that your router is OK, you have to call your ISP and inform theme about your issue, maybe you have some issue on your line,

try with other devices, if all of them having the same issue then it is % the issue reside in the access point or the internet router or your ISP

The notification ‘Limited or No Connectivity’ or any other such text means that the computer is connected to the network but it is unable to connect to the Internet. Likely reasons for this issue may be the non-responsive DHCP server. When the DHCP server fails to assign the IP address to a computer, the computer automatically assigns an IP address to itself. This IP address starts with..x.x and has the subnet mask of..0.0, and the computer displays a notification ‘Limited or No Connectivity’.

If multiple computers depend on the DHCP server to obtain the IP addresses from it and the DHCP server fails, all computers get the IP addresses from the same..x.x range where .x.x is a randomly generated unique number for each computer.

In order to resolve this issue, you can:

    Check if the modem to which your computer is connected is properly configured. If not, you must contact the concerned person and get it reset as per the recommended settings instantaneously.

    Assuming that the modem settings are correct, check that your computer is configured to obtain the IP address, default gateway, and DNS server address from the DHCP server. (In most scenarios where a single modem is used to provide the Internet connection at homes, the modem itself plays the role of the DHCP and DNS server).