Xfinity - Comcast - Static IP Issue

SteveITS · Jan 28, 2022, 9:17 PM

@denverdesktopssupport So you're replacing the Comcast router? What connects to their physical cable?

If you're behind their router it should work in bridge mode unless something is wrong on their end.

If you configure pfSense WAN for DHCP does it pick up a 10.1.10.x WAN address and connect out? Just to see if it functions.

I was referring to replacing an existing router that is already behind a Comcast router.

DenverDesktopsSupport · Jan 28, 2022, 9:30 PM

The Comcast router is not being replaced. That is currently what is handing out 10.1.10.x. Yes, if the PFsense WAN interface is set to WAN DHCP and the router is in "standard mode" it grabs a 10.1.10.x. It does not work when in bridged more or what Comcast calls passive mode.

akuma1x · Jan 28, 2022, 10:01 PM

@denverdesktopssupport Your pfsense box probably isn't working when the Comcast modem is in bridged or passive because, when you switch it to this mode, you need specific info from the ISP.

Mine is in this mode and I needed to contact them to get the following:

WAN IP address (to use in pfsense)
Gateway IP Address
Subnet Mask
DNS servers (should not be required, but maybe)

Do you have any of that info from Comcast? If you do, then you can setup your pfsense WAN interface to use this info and it should get you online. If you do not, you can still use DHCP from Comcast on your WAN interface, you just need to use some other private IP address space on your internal LAN network - 192.168.X.X or 172.16.X.X for example. I have always found it best to NOT use the 10.X space when the ISP also uses a DHCP server in the same space. It's easier to troubleshoot problems when the address space doesn't look similar.

DenverDesktopsSupport · Jan 31, 2022, 3:49 PM

I have the static from Comcast and it has been entered into the WAN interface on the Netgate. That is the issue as it is not working.

akuma1x · Jan 31, 2022, 3:49 PM

@denverdesktopssupport And how about the gateway info? Did you put that into pfsense?

What happens if you plug a PC (laptop) directly into the Comcast modem? Do you get an IP address and DNS from the modem? Can the laptop browse the internet?

You're missing something here, this works either using DHCP from the Comcast modem, or using the static settings (all of them) setup into pfsense.

DenverDesktopsSupport · Jan 31, 2022, 8:59 PM

Configuring my LAN interface with the public static IP provided by Comcast, gets me online. It does not want to pass through to the PFsense WAN interface.

A Former User · Jan 31, 2022, 9:01 PM

@denverdesktopssupport Could you test? and publish logs (so we can help you better)

I would like it to be more specific, explain how each thing is physically connected, ok?

stephenw10 · Feb 1, 2022, 3:56 PM

@denverdesktopssupport said in Xfinity - Comcast - Static IP Issue:

Configuring my LAN interface with the public static IP provided by Comcast, gets me online.

The Comcast router LAN?

Can you connect a laptop directly to9 the CC router when it's in 'bridge mode' and use the static IP?

This seems like the Comcast device is not correctly configured for your static IP. That doesn't seem that uncommon, there are a number of threads like this. Is this the first time that connection is using a static IP?

Steve

DenverDesktopsSupport · Feb 1, 2022, 4:14 PM

Bridged mode doesn't work at all. Passive move is supposedly the correct method of configuration, but that isn't playing nice either. However, yes I can assign the LAN of my laptop the WAN IP address and can connect to the internet.

I agree, I think something is going on with the Comcast device. The WAN interface connection on the PFsense is pretty straight forward. One thread stated to just turn off DHCP and the firewall off on the Comcast router and that did the trick.

Going back out tomorrow morning, weather permitting and can hopefully provide more detail if need be.

Thanks
DenverDTS

DenverDesktopsSupport · Feb 1, 2022, 4:30 PM

@stephenw10 and yes, first time using a static IP at this site.

stephenw10 · Feb 1, 2022, 5:08 PM

@denverdesktopssupport said in Xfinity - Comcast - Static IP Issue:

However, yes I can assign the LAN of my laptop the WAN IP address and can connect to the internet.

Hmm, there really shouldn't be any difference between that and pfSense using it. Other than the MAC address which should be fine with a reboot in between.

Steve

DenverDesktopsSupport · Feb 1, 2022, 5:37 PM

@stephenw10 agreed.

stephenw10 · Feb 1, 2022, 5:55 PM

Well I'd checking the ARP table for any devices on the WAN. Running a pcap on WAN to see if anything appears there.

DenverDesktopsSupport · Feb 3, 2022, 3:09 PM

Well not sure exactly what the issue was, but after doing a restore of the PFsense backup, the device is working as expected. WAN port is up, client is happy and earth is back on axis. :)

FYI - no need to put the Comcast router in passive mode. Just turn off DHCP/Firewall and Wifi.

Thanks for the assistance!!

smartinesmir · Mar 1, 2023, 9:52 PM

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