DNS setting for openVPN for using remote desktop

I have this error when make mac OSX remote desktop connect via VPN(by openVPN) to remote desktop server(windows)

mac OSX(local) -> openVPN(on rent VPS service) -> Windows10

error is here below

An error occurred while communicating with the Remote Desktop Gateway. If this keeps happening, contact your network administrator for assistance.
Error code: 0x3000008

I can use internet via this VPN without problems.

I googled around and guessing this might be relevant with DNS.

(I should not use google dns?? but why?)

my /etc/openvpn/server/server.conf is like this below.

Does anyone have any hint?

local 153.126.111.11
port 1194
proto tcp
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh.pem
auth SHA512
tls-crypt tc.key
topology subnet
server 10.8.0.0 255.255.255.0
push "redirect-gateway def1 bypass-dhcp"
ifconfig-pool-persist ipp.txt
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
cipher AES-256-CBC
user nobody
group nogroup
persist-key
persist-tun
verb 3
crl-verify crl.pem

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