Can’t connect to modem

[Joshaleth]

Just had my modem serviced and now I can’t connect the Orbi router to the server.

Have tried reset and set up.

Help!

[CrimpOn]

Please explain what the modem is (brand and model number) and what the "service" was (replaced?).

Does the modem have more than one ethernet jack on it?

Is the yellow port on the router connected to the modem?

Sometimes, it matter what sequence is used to power up.  i.e. Unplug both modem and router.  Plug in the modem and wait for it to complete startup.  Then, plug in the router.

[Joshaleth]

Xfinity dual band wifi 802.11ac
Mode number: dpc3941T

They had to fix a cable but it’s still the same
Modem. They put it into bridge mode (I thought it already was but now I don’t know if it actually was previously)

The modem has 4 Ethernet ports and it’s plugged into the first one

[Joshaleth]

I have unplugged/ plugged both modem and router In Various orders and I have also reset both

[CrimpOn]

"Back to basics".  Do you have a PC or Mac that can be "literally" plugged into the modem (with the ethernet cable that is currently being used by the Orbi)?  If so, disconnect the Orbi, plug in the computer, restart the modem, then start up the computer.

If the computer goes on-line and works, the modem is good.  Please discover the IP address that the modem gives your computer.

on PC, open a command window and type "ipconfig /all" (no quotes).  The IP address of your computer should NOT begin with 192.168 or with 10.0

[Joshaleth]

The computer won’t go online when connected via Ethernet, but isnt that to be expected since the modem is in bridge mode?

[Joshaleth]

Wait, I got that to work. For an IPv4 address it says: 10.229.78.135 (preferred)

[CrimpOn]

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@Joshaleth wrote:
Wait, I got that to work. For an IPv4 address it says: 10.229.78.135 (preferred)

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10.229.178.135 is a "private" IP space.https://www.lifewire.com/what-is-a-private-ip-address-2625970

If the modem is actually in "bridge mode", the computer should get a "public" IP address, unless there is something "different" about Xfinity.

Aside from that, with the computer connected to the modem, does the computer "work" as far as accessing the internet goes?

[Joshaleth]

Yes, the computer accesses the internet

Thanks so much btw. Much appreciated!

[CrimpOn]

Ok, the computer gets a private IP address when directly connected to the Xfinity, that means the Xfinity is not in bridge mode.  Alas, sometimes technicians mean well, but are not competent in every detail.  Does it appear that the Xfinity is broadcasting a WiFi signal?  If so, that is further proof that it is acting as a router. 

If the Xfinity is a router, you can disconnect the Orbi from the Xfinity, connect to the Orbi with the wired computer, and place the Orbi in Access Point (AP), then reconnect it to the Xfinity.

[Joshaleth]

When I go on to the xfinity app it does say it’s on bridge mode plus the modem no longer lights up the 2.4 and 5 ghz lights

[Joshaleth]

On the other hand, I am seeing the xfinity wifi and can use it to access the internet...

[Joshaleth]

How do you place the Orbi in access point? Using the orbI app?

[Joshaleth]

Okay, it IS in bridge mode. Somehow you can still see an unprotected xfinity wireless, but not the secured one.

So if it is in bridge mode, what do I do to get the orbI working?

[Joshaleth]

Okay, I heard from xfinity and they said that their bridge mode always has a private ivp. So, I turned off bridge mode and trued to set up the orbI but it still says no internet connection. About ready to return the orbI.

[CrimpOn]

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@Joshaleth wrote:
How do you place the Orbi in access point? Using the orbI app?

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I am unaware of a way to change Orbi "mode" using the app.  Connect the computer to one of the ethernet ports on the back of the Orbi. Then open a web browser and use it to connect to the Orbi web interface.  On the Advanced Tab->Advanced Setup->Router/AP Mode.

Alas, having zero experience with Xfinity has left me inadequate to offer a solution.  Bridge mode giving a private address is a foreign concept to me, as is "we turned off the WiFi, but oh yes, we left the WiFi on."  To me, on and off are sort of mutually exclusive.