A router is misconfigured. Figure out which one and fix it. To understand why it fails, you need to know that a subnet mask of 254 in the final octet gives you only two IP addresses. The lowest is reserved for the network and the highest is reserved for the broadcast address. That does not leave any room for IP addresses, making it invalid. 1024 1024 100 True 4 1 197 full firewall0 100 176 110,250 firewall False False 172.16.1.1 0.0.0.0 0.0.0.0 gw lo lo0 176 177 firewall0 lo0 lo 177 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip wan wan0 176 180 firewall0 wan0 wan 180 False wan0 172.16.1.2 255.255.255.252 0.0.0.0 ip eth eth0 176 178 firewall0 eth0 eth 178 False eth0 192.168.1.1 255.255.255.0 0.0.0.0 ip vpn vpn0 176 195 firewall0 vpn0 vpn 195 False Key 172.16.1.18 255.255.0.0 0.0.0.0 ip_only vpn0 192.168.50.1 255.255.255.0 0.0.0.0 ip 192.168.2.1 255.255.255.0 192.168.50.2 route firewall1 100 181 730,250 firewall False False 172.16.1.17 0.0.0.0 0.0.0.0 gw lo lo0 181 182 firewall1 lo0 lo 182 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip wan wan0 181 185 firewall1 wan0 wan 185 False wan0 172.16.1.18 255.255.255.252 0.0.0.0 ip eth eth0 181 183 firewall1 eth0 eth 183 False eth0 192.168.2.1 255.255.255.0 0.0.0.0 ip vpn vpn0 181 196 firewall1 vpn0 vpn 196 False Key 172.16.1.2 255.255.255.0 0.0.0.0 ip_only vpn0 192.168.50.2 255.255.255.0 0.0.0.0 ip 192.168.1.1 255.255.255.0 192.168.50.1 route net_switch0 100 112 109,397 net_switch False False 192.168.1.1 255.255.255.0 0.0.0.0 gw lo lo0 112 113 net_switch0 lo0 lo 113 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip management_interface management_interface0 112 114 net_switch0 management_interface0 management_interface 114 False management_interface0 192.168.1.4 255.255.255.0 0.0.0.0 ip port port1 112 115 net_switch0 port1 port 115 False port1 0.0.0.0 0.0.0.0 0.0.0.0 ip port port2 112 116 net_switch0 port2 port 116 False port2 0.0.0.0 0.0.0.0 0.0.0.0 ip port port3 112 117 net_switch0 port3 port 117 False port3 0.0.0.0 0.0.0.0 0.0.0.0 ip port port4 112 118 net_switch0 port4 port 118 False port4 0.0.0.0 0.0.0.0 0.0.0.0 ip port port5 112 119 net_switch0 port5 port 119 False port5 0.0.0.0 0.0.0.0 0.0.0.0 ip port port6 112 120 net_switch0 port6 port 120 False port6 0.0.0.0 0.0.0.0 0.0.0.0 ip port port7 112 121 net_switch0 port7 port 121 False port7 0.0.0.0 0.0.0.0 0.0.0.0 ip net_switch1 100 122 730,410 net_switch False False 192.168.2.1 255.255.255.0 0.0.0.0 gw lo lo0 122 123 net_switch1 lo0 lo 123 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip management_interface management_interface0 122 124 net_switch1 management_interface0 management_interface 124 False management_interface0 192.168.2.4 255.255.255.0 0.0.0.0 ip port port1 122 125 net_switch1 port1 port 125 False port1 0.0.0.0 0.0.0.0 0.0.0.0 ip port port2 122 126 net_switch1 port2 port 126 False port2 0.0.0.0 0.0.0.0 0.0.0.0 ip port port3 122 127 net_switch1 port3 port 127 False port3 0.0.0.0 0.0.0.0 0.0.0.0 ip port port4 122 128 net_switch1 port4 port 128 False port4 0.0.0.0 0.0.0.0 0.0.0.0 ip port port5 122 129 net_switch1 port5 port 129 False port5 0.0.0.0 0.0.0.0 0.0.0.0 ip port port6 122 130 net_switch1 port6 port 130 False port6 0.0.0.0 0.0.0.0 0.0.0.0 ip port port7 122 131 net_switch1 port7 port 131 False port7 0.0.0.0 0.0.0.0 0.0.0.0 ip pc1 100 109 730,730 pc False False 192.168.2.1 255.255.255.0 0.0.0.0 gw lo lo0 109 110 pc1 lo0 lo 110 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 109 111 pc1 eth0 eth 111 False eth0 192.168.2.3 255.255.255.0 0.0.0.0 ip pc2 100 152 110,700 pc False False 192.168.1.1 0.0.0.0 0.0.0.0 gw lo lo0 152 153 pc2 lo0 lo 153 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 152 154 pc2 eth0 eth 154 False eth0 192.168.1.3 255.255.255.0 0.0.0.0 ip router0 100 186 150,80 router False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 186 187 router0 lo0 lo 187 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 186 188 router0 eth0 eth 188 False eth0 172.16.1.1 255.255.255.252 0.0.0.0 ip eth eth1 186 189 router0 eth1 eth 189 False eth1 172.16.1.5 255.255.255.252 0.0.0.0 ip 172.16.1.18 255.255.255.252 172.16.1.6 route router2 100 160 360,300 router False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 160 161 router2 lo0 lo 161 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 160 162 router2 eth0 eth 162 False eth0 172.16.1.6 255.255.255.252 0.0.0.0 ip eth eth1 160 163 router2 eth1 eth 163 False eth1 172.16.1.9 255.255.255.254 0.0.0.0 ip 172.16.1.2 255.255.255.252 172.16.1.5 route 172.16.1.18 255.255.255.252 172.16.1.10 route router3 100 164 450,10 router False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 164 165 router3 lo0 lo 165 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 164 166 router3 eth0 eth 166 False eth0 172.16.1.10 255.255.255.252 0.0.0.0 ip eth eth1 164 167 router3 eth1 eth 167 False eth1 172.16.1.13 255.255.255.252 0.0.0.0 ip 172.16.1.2 255.255.255.252 172.16.1.9 route 172.16.1.18 255.255.255.252 172.16.1.14 route router4 100 168 720,90 router False False 0.0.0.0 0.0.0.0 0.0.0.0 gw lo lo0 168 169 router4 lo0 lo 169 False lo0 127.0.0.1 255.0.0.0 0.0.0.0 ip eth eth0 168 170 router4 eth0 eth 170 False eth0 172.16.1.14 255.255.255.252 0.0.0.0 ip eth eth1 168 171 router4 eth1 eth 171 False eth1 172.16.1.17 255.255.255.252 0.0.0.0 ip 172.16.1.2 255.255.255.252 172.16.1.13 route 122 125 net_switch1 port1 181 183 firewall1 eth0 191 109 111 pc1 eth0 122 127 net_switch1 port3 151 186 189 router0 eth1 160 162 router2 eth0 193 152 154 pc2 eth0 112 118 net_switch0 port4 159 160 163 router2 eth1 164 166 router3 eth0 173 164 167 router3 eth1 168 170 router4 eth0 175 112 117 net_switch0 port3 176 178 firewall0 eth0 190 176 180 firewall0 wan0 186 188 router0 eth0 192 181 185 firewall1 wan0 168 171 router4 eth1 194 pc2 pc1 SuccessfullyPings