What you’re seeing
- The firewall's WAN interface shows a private address such as 192.168.x.x or 10.x.x.x instead of a public IP.
- Port forwards for cameras, remote desktop or a server never seem to work, no matter how they are set.
- Site-to-site or remote-access VPNs fail to connect or drop repeatedly.
- Gaming consoles or VoIP phones report 'Strict NAT' or 'NAT type 3' messages.
- Phone calls have one-way audio, and online services that need inbound connections behave unpredictably.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The ISP's modem is a combination modem-router that is still doing routing and NAT in front of your firewall.
- A replacement ISP gateway was installed and reverted to its default router mode.
- Bridge mode or IP passthrough is not supported on the ISP's equipment without a business plan.
- A second consumer router was added behind the firewall to extend Wi-Fi and is also translating addresses.
- Fiber or cellular providers sometimes use carrier-grade NAT, so the office never receives a true public IP.
Why it matters
Double NAT rarely causes a total outage, which is why it can go unnoticed for months. Instead it breaks the services that need traffic to come into the office: VPNs for remote staff, remote access to security cameras, hosted phone systems and servers that customers connect to. The resulting faults are intermittent and confusing, so businesses often pay for repeated troubleshooting on the wrong device. It also complicates security, because rules on the ISP box can expose or block things your firewall never sees.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Is double NAT a security risk?
Not directly, but it means two devices are making decisions about your traffic, and the ISP device is often poorly maintained. It also makes it harder to know what is truly exposed to the internet.
Do I need to call my internet provider?
Sometimes. Some ISP gateways can be switched to bridge or passthrough mode by the customer, while others need the provider's help or a different plan.
Can AskTechGurus untangle this for us?
Yes. A certified US engineer can review your firewall and ISP equipment over a remote secure session, starting at $99, and you pay only when it is resolved.