VPN over ethernet, Internet over wifi

Step 1, create two plain text files named ip-up and ip-down in /etc/ppp and make the two files executable:

$ sudo touch /etc/ppp/ip-{up,down}
$ sudo chmod +x /etc/ppp/ip-{up,down}

Step 2, modify the file ip-up, add the following:

#!/bin/sh
export PATH="/bin:/sbin:/usr/sbin:/usr/bin"

OLDGW=`netstat -nr | grep '^default' | grep -v 'ppp' | sed 's/default *\([0-9\.]*\) .*/\1/'`

if [ ! -e /tmp/pptp_oldgw ]; then
    echo "${OLDGW}" > /tmp/pptp_oldgw
fi

dscacheutil -flushcache
route add 10.4.0.0/24 "${OLDGW}"

Step 3, modify the ip-down, add the following:

#!/bin/sh
export PATH="/bin:/sbin:/usr/sbin:/usr/bin"

if [ ! -e /tmp/pptp_oldgw ]; then
        exit 0
fi

ODLGW=`cat /tmp/pptp_oldgw`

route delete 10.4.0.0/24 "${OLDGW}"
rm /tmp/pptp_oldgw

I have the exactly same issue on both Wi-fi and Ethernet connections. It started after upgrading from Maverick to Yosemite and all my VPN connection were behaving the same.

I got in touch with Apple support regarding this problem and their procedure was as follows:

1. Create a new network location (which gives us fresh network settings to work with)
2. Create the VPN connection in this new location
3. Test

If the problem persists (my situation) then your old settings are not the problem.

4. Create a new user (administrator rights)
5. Log in with this new user
6. Test again

If your problem persists (my situation) then your user settings are not the problem.

At this stage they said the problem should be the VPN providers, but in my situation nothing was changed from their end and I am using their services for more than a year now.

Continuing my research I suspected the problem should be DNS related. I can ping external addresses by IP, but not by DNS, and my local network still works.

As a temporary solution I entered my router's address in the VPN DNS Servers.