Secondary IP on one interface (Debian 8)

Im trying to add a secondary IP on an old Debian 8 server at work and have an issue. The setup look like this (just the IP parts in /etc/networking/interfaces):

auto eth0
allow-hotplug eth0
iface eth0 inet static
    address 192.168.0.10
    netmask 255.255.255.0
    gateway 192.168.0.1

auto eth0:0
allow-hotplug eth0:0
iface eth0:0 inet static
    address 10.10.0.10
    netmask 255.255.255.0
    gateway 10.10.0.1

When I restart the networking services everything seems to work as a charm and ifconfig shows everything as it should. Its also correct when i loook at the routing-table with "route -n". The problem is that I cant access the server using the new IP. I cant ping it and I cant access it through http/https (its a webserver). Even Nutanix is showing that the server got two IPs. Am I missing something or is this something that might have to be fixed in the firewall (not on the server)?