Invalid default gateway (RTF_IFSCOPE), route not found

Hello everyone,

TLDNR: On a macbook air on Yosemite , on a specific AP, I receive 1 (and only 1) default gateway that is set as 'UGScI'. That seems to prevent me to go anywhere outside of the AP IP range... What would cause that? (same problem as: http://osquestions.com/osx-ios/167303/wireless-automatically-gets-rtf-ifscope-de fault-route, but no one answered! and I haven't found another one like this.)

I have a problem that I currently am working on. I've been trying to figure out what is going on, but can't seem to fix it.

I have 2 different WIFI setups and 2 different MacBook (1 pro late 2013/1 air mid2013 i think). They are both on Yosemite (10.10.4).

When connecting on Wifi setup #1 (AP #1, network #1), they both get their routes straight. The "netstat -nr" command returns (for both, and obviously, the specific ip to the machine changes...):

Routing tables

Internet:

Destination Gateway Flags Refs Use Netif Expire

default 192.168.69.1 UGSc 23 0 en0

127 127.0.0.1 UCS 0 0 lo0

127.0.0.1 127.0.0.1 UH 2 128311 lo0

169.254 link#4 UCS 0 0 en0

192.168.69 link#4 UCS 1 0 en0

192.168.69.1/32 link#4 UCS 2 0 en0

192.168.69.1 FAKE_MAC_VALUE UHLWIir 21 60 en0 1096

192.168.69.105/32 link#4 UCS 0 0 en0

When connecting to Wifi Setup #2 (AP #2, network #2), the difference (other than the machine's IP and the subnet...) is that in one case, the default gateway has flags 'UGSc' and the other has flags 'UGScI' (for the same AP):

Routing tables

Internet:

Destination Gateway Flags Refs Use Netif Expire

default 192.168.68.1 UGScI 0 0 en0

127 localhost UCS 0 0 lo0

localhost localhost UH 2 128287 lo0

169.254 link#4 UCS 0 0 en0

192.168.68 link#4 UCS 0 0 en0

192.168.68.1/32 link#4 UCS 2 0 en0

192.168.68.1 FAKE_MAC_VALUE UHLWIi 1 8 en0 1199

192.168.68.4/32 link#4 UCS 1 0 en0

So... what I found out is that on the computer (macbook air) with the I flag (RTF_IFSCOPE), I cannot route to anything outside the IP range received by DHCP.

ex:

ping 8.8.8.8 (or even any other subnet) gives error : 'ping: sendto: No route to host'

If I set a new default gateway manually (without the I flag), it works and I can reach the other subnets. So why in that case, the flag is set and the the other one?

Also, on both laptop:

>sysctl net.inet.ip.scopedroute

net.inet.ip.scopedroute: 1

And on the macbook pro (the one that works on both AP), 'route -n get default' works fine both on the macbook air, I get: 'route: writing to routing socket: not in table'...

Also, I have other devices (Windows) that are running perfectly fine on the AP2...

So... I have completely out of ideas... if anyone can help? 🙂

Regards,

Maxime