This is very strange because it is no problem in Windows and the remote option is specified (see below). Is this a bug in the Android app (OpenVPN Connect)? I obtained the .ovpn file from a Synology NAS configuration.
My .ovpn file looks like this:
dev tun
tls-client
remote my.ddns.com 1194
# The "float" tells OpenVPN to accept authenticated packets from any address,
# not only the address which was specified in the --remote option.
# This is useful when you are connecting to a peer which holds a dynamic address
# such as a dial-in user or DHCP client.
# (Please refer to the manual of OpenVPN for more information.)
#float
# If redirect-gateway is enabled, the client will redirect it's
# default network gateway through the VPN.
# It means the VPN connection will firstly connect to the VPN Server
# and then to the internet.
# (Please refer to the manual of OpenVPN for more information.)
#redirect-gateway def1
# dhcp-option DNS: To set primary domain name server address.
# Repeat this option to set secondary DNS server addresses.
#dhcp-option DNS DNS_IP_ADDRESS
pull
# If you want to connect by Server's IPv6 address, you should use
# "proto udp6" in UDP mode or "proto tcp6-client" in TCP mode
proto udp
script-security 2
reneg-sec 0
cipher AES-256-CBC
auth SHA512
auth-user-pass
auth-nocache
<ca>
-----BEGIN CERTIFICATE-----
ABCDEFGHIJ
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
KLMNOPQRST
-----END CERTIFICATE-----
</ca>