Linux – VPN client can ping LAN machines but no other TCP/UDP service works

After just having succesfully configured my VPN server to connect my VPN clients to my LAN ( Expose internal LAN to VPN using CentOS FirewallD ) I find that pinging is the only thing that works. I can't reach any machine that I can ping over SSH, HTTP, FTP, or other services.

Some background info:

On the server:
The machine is a CentOS 7 install that runs Tinc VPN.

 #firewall-cmd --get-active-zones 
internal
  interfaces: eth0 (192.168.178.0/24)
external
  interfaces: vpn (10.0.0.0/24)

The client is a Fedora 21 machine that connects to the VPN server from varying locations (3G for example).

[root@chlorine hosts]# ssh 192.168.178.21
ssh: connect to host 192.168.178.21 port 22: No route to host
[root@chlorine hosts]# wget 192.168.178.21
--2015-01-06 00:52:50--  http://192.168.178.21/
Connecting to 192.168.178.21:80... failed: No route to host.
[root@chlorine hosts]# ping 192.168.178.21
PING 192.168.178.21 (192.168.178.21) 56(84) bytes of data.
64 bytes from 192.168.178.21: icmp_seq=1 ttl=63 time=119 ms
64 bytes from 192.168.178.21: icmp_seq=2 ttl=63 time=135 ms

Ping to any machine works. LAN machines can also ping VPN machines just fine. Anything other than ping however, fails. Does not seem to be a firewall issue at least on either clients sides. Does anyone have a clue? Things I could try?

PS: Traceroute from the VPN client to a LAN host and the vpn server's lan port:

    [alex@chlorine ~]$ traceroute 192.168.178.1
traceroute to 192.168.178.1 (192.168.178.1), 30 hops max, 60 byte packets
 1  10.0.0.60 (10.0.0.60)  128.311 ms  130.495 ms  182.502 ms
 2  10.0.0.60 (10.0.0.60)  184.198 ms !X  188.066 ms !X  190.507 ms !X

    [alex@chlorine ~]$ traceroute 192.168.178.47
traceroute to 192.168.178.47 (192.168.178.47), 30 hops max, 60 byte packets
 1  192.168.178.47 (192.168.178.47)  127.881 ms !X  129.314 ms !X  133.072 ms !X

The "!X" in the traceroute seems to mean "Communication Administratively Prohibited", which seems to imply firewall issues, however on I've disabled/opened the firewalls everywhere as much as possible to rule it out:

VPN server:

[root@zinc ~]# firewall-cmd --list-ports --zone=external
1024-65535/tcp 1024-65535/udp
[root@zinc ~]# firewall-cmd --list-ports --zone=internal
1024-65535/tcp 1024-65535/udp 656/udp 655/tcp 655/udp 656/tcp

I've been trying to reach a Windows box that has its firewalls completely disabled at 192.168.178.37, however with the same results as every other LAN machine; Ping works, the rest does not, traceroute says "Communication Administratively Prohibited."
Any more ideas? Thanks for the help so far! This is strange and hard to diagnose properly for me.