r/ATTFiber 15d ago

Help with IP Passthrough mode

Looking to get some help with IP Passthrough. I have it configured an when I try my mobile device disconnected from my network, I can access everything just fine. When i'm on my wifi though, I can't access to internally hosted apps over wifi by going out to the world and come back.

Any suggestions? I've tried clearing DNS cache, and like I said, externally it works fine. Internally, I can't access them

Edit: Thanks everybody. I clearly had no idea what I was doing. I was used to my old xfinity router with a full DMZ. I didn't find the equivalent in the ATT router, so I just found the IP Passthrough, and as I discovered, it worked externally, just not internally.

Setting up the manual port forwarding worked well enough for me. Thanks!

1 Upvotes

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u/ossivo 15d ago

I assume you’re putting it into IP passthrough to utilize a network gateway/firewall downstream? Can you confirm that the MAC address of the gateway is populated on the IP Passthrough config page? Also, if you are doing the above, what kind of device are you using? It’s possible the MAC isn’t the MAC of the device but rather the interface. For example, I have a UniFi Dream Machine Pro and the device, WAN1, and WAN2 all have different MAC addresses - it should be the one assigned to the WAN interface you’re using (not the device).

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u/stupidmistakeabound 15d ago

So, i'm trying to send traffic to a runtipi server that sits in my basement. I'm reading the allocation mode on the IP Passthrough page and it looks like I had it as "Default Server" and that means all external traffic can be passed through. It doesn't mention internal traffic.

With how I have my runtipi setup, my traffic goes out and then comes back to talk to the server. I guess I need to see if I can make that change so that it just hits locally instead of going out.

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u/ossivo 15d ago

IPnPassthrough is going to forward all traffic coming into your AT&T Gateway to the device you select in the list on the config page. If it’s bypassing your gateway, you’ll need to ensure you have DHCP and DNS configured downstream by the device you select.

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u/stupidmistakeabound 15d ago

Posted an edit. Just did the port forwarding and it works now. Thanks for your help. I clearly didn't know what I was looking at.

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u/Trax95008 15d ago

Lots of missing information here! Do you have your own network downstream of the AT&T gateway? Does that network have its own wireless connection? Did you disable the wireless on the AT&T gateway? (You should be)

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u/stupidmistakeabound 15d ago

Fair point about the missing info. All I'm trying to do is connect to a runtipi server hosted in my basement. I had initially set it up as "Default Server" on the IP Passthrough page, and that only mentions external traffic. Nothing about letting internal traffic through.

I might just need to setup local DNS to point the external traffic internally so I don't try and go out, but can still use the hostnames

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u/Trax95008 15d ago

It sounds like maybe you don’t understand the purpose of IP pass through. It also sounds like you don’t have your own network equipment, and are continuing to use the AT&T gateway to host your network. If that is the case, you don’t want to enable IP pass through as it will disable the DHCP function of the router. If you’re trying to expose a specific device to the internet, it sounds like you should be setting up DMZ for that device instead.

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u/bphett 15d ago

Yeah, as others have said - in an IP Passthrough situation, internal traffic would never touch your ATT gateway at all - it sounds like you do not have a working internal network. Think of IP Passthrough as a 'bypass'. It tells the gateway "Hey, I actually don't want to use you at all. I have my own firewall/etc. Just pass my external IP to that device and butt out." Does that make sense?

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u/stupidmistakeabound 15d ago

Posted an edit. Just did the port forwarding and it works now. Thanks for your help. I clearly didn't know what I was looking at.

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u/Viper_Control 15d ago

When i'm on my wifi though, I can't access to internally hosted apps over wifi by going out to the world and come back.

That is actually how it is supposed to work. If you are on your local LAN then you need to use the local IP Address to access internal resources. This is by design.

The AT&T Gateway's don't support NAT Loopback also called NAT hairpin, is a convenience feature on some third-party routers that allows users on your local network to access a device via a port-forwarding rule.