I have found a way to fix my error, my previous VPS is from vpsserver can’t accept to run fullnode because they are not allowed to abuse the CPU. Bitcoin Mining uses allot of CPU performance and they not allowed.
I already using another VPS provider from bithost, all the installation is doing correctly & I was able to run bitcoind and other bitcoin-cli command, but after edit the bitcoin.conf file and append the following I found the error box still showing in my plugin page. I have following the instruction by replace the IP address from my server & change the rpc/rpcpassword