When I hit that address, I get a page informing me that I'm not connected to my router's wi-fi network. I'm assuming you probably are connected to your Netgear's wi-fi network or you would get that page, too, instead of a failure to connect.

There's an internal page you can use for testing network-related things. Type or paste the following in the address bar and press Enter/Return to submit it:

about:networking#dnslookuptool

If DNS Lookup isn't selected in the left column, click it.

Then try www.routerlogin.net there to see whether Firefox is able to retrieve the expected local IP address. Any luck?

Note: if DNS isn't working AND you are using DNS over HTTPS, you may need to create an exception for this hostname. To do that:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste TRR and pause while the list is filtered

(3) Double-click the network.trr.excluded-domains preference to display a dialog where you can enter or edit host names:

• if this field is blank: type or paste www.routerlogin.net and click OK

• if this field is not blank: type or paste a comma, and then (with no space) type or paste www.routerlogin.net and click OK

That should prevent Firefox from using the DoH resolver to look up your local router address.

It sounds that there is a problem with doing a DNS lookup for local website.

Did you recently changed the DNS server (VPN or Proxy or DoH) that could be causing this?

The iMac is connected to the router/modem over ethernet or, more specifically, ethernet over powerline - never caused any issues before.

Thanks for about:networking, never knew that existed. I keep discovering things in Firefox I didn't know about.

If I enter www.routerlogin.net it returns 10.175.0.1

Entering www.routerlogin.net into the address bar still gives me the Unable to Connect Page, entering 10.175.0.1 connects with no problem .....

Safari still connects with either form of the address, so I don't see that it's anything to do with the DNS lookup?

I've made no changes of which I'm aware to the network setup.

Network.trr.excluded-domains shows localhost,local which doesn't sound right .... Adding www.routerlogin.net seems to have no affect, although perhaps I need to restart Firefox?

UKLarry said

Thanks for about:networking, never knew that existed. I keep discovering things in Firefox I didn't know about.
If I enter www.routerlogin.net it returns 10.175.0.1
Entering www.routerlogin.net into the address bar still gives me the Unable to Connect Page, entering 10.175.0.1 connects with no problem

I can't explain that. If Firefox knows the IP address corresponding to the host name, why doesn't it connect using the host name??

jscher2000 said

UKLarry said

Thanks for about:networking, never knew that existed. I keep discovering things in Firefox I didn't know about.
If I enter www.routerlogin.net it returns 10.175.0.1
Entering www.routerlogin.net into the address bar still gives me the Unable to Connect Page, entering 10.175.0.1 connects with no problem

I can't explain that. If Firefox knows the IP address corresponding to the host name, why doesn't it connect using the host name??

Beats me as well!

Got to be something to do with Firefox as it's not an issue with Safari.

I'm just wondering if there's something in the modem/router doing the blocking, although it's odd it's only applying it to Firefox and not Safari. Rebooting the router didn't help so I'm thinking on trying a factory reset of the router.

Did a factory reset of the modem/router - problem remains :-(