Static IP + IP Passthrough (FSNO21VA) MTU Fix

VPN
1

Hey all,

I’ve been following this sub for a while as we have a shitload of the OG gateway 1.0/cubes deployed. We do not have static IPs with those, however I had tried using IPPT. We encountered so many issues with the MTU config, that we ultimately went back through and enabled the DHCP/NAT’ing through the cubes.

Flashforward to now when I needed to deploy a 2.0 FSNO21VA gateway. I needed a static IP and also needed IPPT to work so I could connect a VPN tunnel. After enabling IPPT, I was pleasantly surprised all things seemed to be working and I got the VPN up. Then, during testing of the network I was greeted with a page cannot load error for literally all Google services - YouTube, Gmail, Google Calendar, etc. I believe there were a few others, but those were the ones I remember.

The fix:

  • Log into your gateway using the public IP - not what your router has configured, but its gateway IP
  • Click the Advanced tab, then expand Network Settings and click Network Connections, then click Edit on the Ethernet network:

2111×1831 66.3 KB

  • Once inside that connection, click Settings:

2594×1869 70.3 KB

  • Next, find the MTU setting and update it to Manual via the dropdown, set it to 1428, and click Apply:

2082×1869 67.1 KB

That’s it. I’ll update if I find any issues with it, but it seems to be doing to trick for me at the moment.

2

1428 is pretty low. You should try the steps outlined here:

— Starfox

3

In this case, I did in fact plug a machine directly into the ARC and ran through the ping testing outlined in your link and many other sites. 1428 was the max. Appreciate the response though! It is helpful for everyone to understand, though I haven’t seen any threads on this sub where people had success above 1428.

4

I’ve done all that. That’s how I got to 1428 for my router.

5

NIS-SDX62-817A-0000-B01

If you have a static IP, then the gateway would be whatever you plugged into your router sitting behind the VZ device. If you’re passing through the public DHCP address from VZ, then you’d have to log into your router and see what gateway it picked up from the VZ device.

6

Oops. That was modem firmware. The router firmware is 3.2.0.10.