Unable to add the Fortigate 200D firewall version 6.0.10.

And below is the error while adding the firewall

1344:20210206:124810.217 SNMP agent item "fortinetCurrentCPUUtil" on host "Firewall" failed: first network error, wait for 15 seconds
1346:20210206:124829.185 SNMP agent item "fortinetCurrentConnections" on host "Firewall" failed: another network error, wait for 15 seconds
1316:20210206:124834.444 item "Firewall:fortinetUsedStorage-percent" became not supported: Cannot evaluate expression: "Cannot evaluate function "last()": not enough data.".
1346:20210206:124848.263 SNMP agent item "fortinetUpTime" on host "Firewall" failed: another network error, wait for 15 seconds
1346:20210206:124907.295 temporarily disabling SNMP agent checks on host "Firewall": host unavailable