Bing hijacking my firefox seaches when duckduckgo

Your entire post is senseless, beginning with the title, except for this

ATT will NOT let me change the DNS on their fiber modem.

That much is accurate: AT&T does impose their own choice of default DNS servers on the Gateway.  However, you are able to manually select the DNS of your choice in your client, or provide your own router behind the Gateway that does its own DNS handling.

I'm sorry if this was over your head. I could break it down into simpler terms for you:

1. Cell phone searches within Firefox, using Duckduckgo as the ONLY search engine selected, would be directed to Bing search results.

2. My PC does not experience this issue because I have the DNS configured on it for Google's nameservers.

3. I enable NordVPN on the cell phone and Firefox search results are no longer hijacked by Bing.

4. I disable WiFi on the cell phone, and use T-mobil data service, NO hijacking occurs. That means Firefox displays duckduckgo results.

5. I put their crappy little modem in pass through, I RE-ENABLED WiFI on the cell phone. Firefox shows duckduckgo results.

That pretty much explains the troubleshooting I've done and the results. There is no doubt in my mind that the Bing hijacking is due to ATT DNS servers.

If you still can't wrap your head around this, do you have a teenager handy to explain it?

Let's both take a step back and stay away from the insults and see if we can figure out what's going on.

I did make the mistake of assuming you were talking about the Duck Duck Go browser app instead of their search engine service launched from a browser.  That's why I didn't think your title made sense.  Thank you for clarifying that.   

Are you putting "their crappy little modem in pass through" to your phone or some intermediate router?

For you to see the behavior you're seeing, when firefox goes to make the search request, it should be sending the DNS name of the search engine service (something like "search.duckduckgo.com") and get back the IP address associated with the equivalent of "search.bing.com" and they have to take the same search syntax (which I think has been standardized to get all the browsers to adopt multiple engines).  However, even that doesn't make sense, because (a) the certificate would be different and (b) the routing on the bing server should say "that's not my site."  For that reason, Firefox must be deciding that it can't get to DuckDuckGo and is falling back to Bing.  Not to say that there's not still a problem with AT&T and getting to Duck Duck Go, but AT&T can't accomplish substituting Bing for it without the browser being complicit.

Okay, I do apologize for my attitude, this issue had given me a headache till I got it working. I have a router behind the ATT modem that is passed through now. With this setup, all devices in house connect to that router only. I left the WAN settings alone and my phone's search still popped up Bing results even though I have all search engines disabled in the Firefox search settings except Duckduckgo. When I manually set my router's WAN DNS to Google, the issue stopped on my phone. I understand how DNS works and the fact that it only happens when using ATT's WAN settings leads me to believe wither they are pushing Bing on me or their nameservers could be hijacked.

I do appreciate your response and I can't think of any other reason this issue occurred.

I agree that there's something up with the the DNS return from AT&T.  The question is... what?

This only happens on your phone?  Would it happen on your PC if directly connected to the Gateway?  If so, then there's some diagnostics we could do (well, on Chrome I would do: open a new browser tab, start developer tools on Network, enter a search term and hit enter and see what the conversation looks like on the Network tab, i.e., what address the request it sent to, etc.; I've never been a big Firefox guy, but I'm assuming you can do the same with Firefox).

It's obvious that AT&T's DNS servers are configured to redirect certain searches to Bing instead of your preferred search engine. But with solution like using your own router with pass-through mode enabled, allowing you to set your preferred DNS servers on your router's WAN settings. This way, you can bypass AT&T's DNS servers and maintain control over your DNS settings.

You cannot just substitute one server for another with a simple DNS redirection, I don't care how obvious you think it is.  That's one reason why servers have certificates, so that you can't just substitute one server for another.  I'm not sure what's going on, but it's not as simple as you think.

@hysn109 

It is not an AT&T DNS issue or there would be thousands of posts here on the Forum. The issue is local to @Jerrdale and their configuration of their secondary router in IP/Passthru mode.

Most likely an issue with the Default LAN DNS default setting on their secondary router as @Jerrdale since they indicate the behavior went away as soon as they update the WAN DNS settings on their secondary router that the phone was connecting via Wi-Fi.

Dave