Site unreachable from local IP

well, thats a first. I’m constantly getting an ERR_NAME_NOT_RESOLVED error on all devices connected to my local network. I’ve been battling these DNS issues for two days now, only to realize my Heroku deployed rails app is unreachable ONLY from my local network (WiFi). when trying to access it through the cellular network - everything works as expected.
Configuring Cloudflare DNSResolver / Google Public DNS seems to resolve ( :sweat_smile: ) the issue, but as I’m not entirely able to understand what causes the problem (absolutely not a DNS expert), I’d like to know if there’s a way to prevent this problematic behavior for other visitors.

Thanks in advance :slight_smile:

Sure. Don’t let them use your home WiFi. :wink:

Do you know the IP addresses of the default DNS servers you were using on your router?

Oh…and the hostname that wasn’t resolving would also help in troubleshooting.


what a great suggestion my friend :rofl:
my default DNS server IP was
as for the hostname, well, I’m just guessing you mean the actual domain:
I’m using CNAME flattening on the root domain and another CNAME record for the “www” subdomain, both pointing to different configured domains on Heroku.

That’s private IP. I believe you checked this info in your PC settings.

Usually when private IP is used for DNS resolve, the private IP is usually your home router.

Check your router settings - it should display the public DNS resolver being used.

I see. thank you for clarifying.
in that case:
IP Address:
Primary DNS:
Secondary DNS:

I guess these are the DNS servers assigned by / use by your ISP.

Hmmm…your domain resolves at both of those name servers. So I don’t know why your devices weren’t able to find your website.

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