Orbi RBK50 + Starlink Invalid Gateway IP Address

[Dishy]

With Starlink, I set a static route to enable the mobile app direct access to the router. I have to update it when the IP changes and this isn't as important now that Starlink app supports remote access, but this is still something I'd like to understand. I've set a static route about 50 times (for new IPs) with no issues and always just took the WAN IP and set it to the Gateway IP in the static route config. Now, for the first time, my Dishy assigned my router an IP ending in .0. Orbi is telling me that it's an invalid gateway IP address. Any ideas?

Here is my config ...

Internet Port
IP Address: 100.65.16.0
Connection: DHCP
IP Subnet Mask: 255.192.0.0

Static Route
Destination IP Address: 192.168.100.0
IP Subnet Mask: 255.255.255.0
Gateway IP Address: 100.x.y.0
Metric: 2

I can put anything but 0 and 255 into that last digit on the gateway IP and it will accept it

[Mikey94025]

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@Dishy wrote:
Now, for the first time, my Dishy assigned my router an IP ending in .0. Orbi is telling me that it's an invalid gateway IP address. Any ideas?

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Wow, I didn't realize that legal IP addresses can end in 0: https://stackoverflow.com/questions/14915188/ip-address-ending-with-zero.  Seems like the Orbi needs to be updated to support such IP addresses.

In the meantime, can you force your Dishy to assigned another IP address to your router (and hope you get one that the Orbi will accept)?

[CrimpOn]

(The best part of this community forum is hearing about unusual situations.)

Could you please provide a little more background about this use of 'static routes', in particular where the static route is being defined. (on Starlink or on Orbi).

The way I understand it, static routes on the Orbi provide a method for devices on the local LAN to find IP addresses that cannot be reached through the usual gateway (the Orbi LAN IP address).  With the typical Orbi subnet mask of 255.255.255.0, when a device wants to communicate with any other device that has the same /24 prefix, it uses ARP to find the MAC address of the device and sends packets directly to it.  When the target device has an IP that is not in the same subnet, it sends packets to the gateway and says, "You figure it out."

Sometimes the Orbi WAN interface has no idea where to find that IP.  In that case, a static route on the Orbi says, "instead of using the Orbi gateway, send packets destined for that IP address to this other gateway on the Orbi LAN.  It doesn't matter what the target IP address ends with, but the 'gateway' has to be an IP on the Orbi subnet.

The way I picture this situation:

Starlink has given the Orbi WAN interface 100.65.16.0 with a subnet mask of 255.192.0.0 (one damn big subnet of 4,194,302 addresses)

Orbi has created a typical subnet of 192.168.1.0 with subnet mask 255.255.255.0 (256 addresses).

Some device on the Orbi LAN needs to connect to 100.x.y.0 and using the regular Orbi gateway cannot find it.

I obviously am misunderstanding something.

[Dishy]

I've tried rebooting both Dishy and the Orbi, but it still hands out the .0 address, probably due to a reservation based on the Orbi's MAC address, which I can't change. I may just have to wait for it to rotate and hope for a non-zero address.

[Dishy]

Yes, the static route is on the Orbi. Starlink provides their own router and you manage Dishy with a mobile app, but many of us need to use our own routers for a variety of reasons. The mobile app is hard-coded to look for Dishy on 192.168.100.0. Dishy is upstream of the Orbi, connected to the Orbi's WAN port. So I need something to tell the Orbi to send the traffic for 192.168.100.0 over the WAN port. It's always been a bit of a pain because that WAN IP for Orbi changes every so often (days or weeks) and I need to update the static route when it does. My understanding of networking is pretty basic, though, so I'm mostly leaning on what other more network-savvy Starlink users have done.

I suspect that the Orbi may not allow a .0 gateway but was hoping that maybe I was attempting something improper with the subnet mask, about in which I know very little. But I guess a .0 Subnet mask should allow all addresses 0 to 255. It's just strange that Netgear wouldn't support the standard 20 years after it's implemented, so I assumed something else must be wrong.

[CrimpOn]

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@Dishy wrote:
So I need something to tell the Orbi to send the traffic for 192.168.100.0 over the WAN port. It's always been a bit of a pain because that WAN IP for Orbi changes every so often (days or weeks) and I need to update the static route when it does

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A static route on the Orbi must point to a LAN port on the Orbi, not the WAN port.  As it is, the Orbi already recognizes that 192.168.100.0 in not on the LAN, and the way to reach that IP address is to use the WAN port.

See page 76 on the RBR50 user manual:

https://www.downloads.netgear.com/files/GDC/RBK50/Orbi_UM_EN.pdf 

[Dishy]

I hear what you're saying and not suggesting that you're incorrect, but I've been doing this for more than a year and it's always worked. All Starlink users with round Dishys who bring their own router must do this to get full functionality in the app. Everyone assigns a static route to your router's WAN IP. It worked with all other IP addresses. It just doesn't like the .0

[KevinLiT]

Hi Dishy,

When assigning a static IP address to a device you have to make sure that the desired IP address is on the same network as all the other devices on the network. The .0 in the fourth octet is a network IP address is not a client IP address. That is why you had configuration issues when trying to assign that IP address to a device in your network. 

Best,

Kevin

community Team

[Dishy]

Thanks, Kevin. I received the same feedback from another user here, but it still doesn't make sense to me. I just got a new IP from my Starlink dish (not a .0 anymore) and I've updated the static route and it's now working. My settings for it are as follows:

Destination IP Address: 192.168.0.1
IP Subnet Mask: 255.255.255.0
Gateway IP Address: 100.x.y.z (removed for privacy)
Metric: 2

What I don't understand is that multiple people are telling me that the Gateway IP must be on the 192.168 network and that's not what's working for me. If I deactivate this static route, then the Starlink app on my phone won't work. With it active, the app works and can communicate with the dish. I can't explain WHY this works, only THAT it works. 🙂 I can also say that every other Starlink user who wants to do this is using these same settings as above and I've now confirmed with 2 different users that their routers of other brands will accept a 100.x.y.0 address as the Gateway IP.

There are some details on this here which go beyond my knowledge level: https://www.reddit.com/r/Starlink/comments/jxkz1q/anyone_know_how_to_get_the_starlink_app_to_work/ and here https://www.reddit.com/r/Starlink/comments/jqhoqz/starlink_app_works_fine_behind_own_router/gby79x1?....

As for me, I'll leave it to you more knowledgeable people to try and understand the details and I'll just hope that I don't get another .0 address from Dishy. 🙂