How to Force Bridge Mode on Airtel Fiber (Sercomm) for Your Mesh Network?

If you are trying to set up a true Mesh network on an Airtel broadband connection, you have likely run into the same frustrating roadblock I did: Airtel aggressively locks down their routers and disables Bridge Mode.

I recently upgraded to an Airtel Fiber 200MBPS connection. They provided the Sercomm AOT 4221SR (a very common GPON router on their network). Because my family lives across three floors i.e., Ground, 1st, and 2nd therefore a single router was never going to cut it. I needed connectivity in every corner of the apartment building, so I built my own mesh network using a TP-Link Deco X10 as the primary router and three Deco M4s as satellite nodes.

The hardware was ready, but the software was standing in the way.

The Problem: The DMZ Trap and Double NAT

When you plug a powerful mesh system into an ISP router, you end up with two devices trying to act as the network “boss.” This creates a Double NAT (Network Address Translation) issue, which can ruin remote access, mess up port forwarding, and cause strict NAT types in gaming.

The standard ISP workaround is to put your mesh router into the ISP router’s “DMZ.” While this technically works, it’s a band-aid. You are still sitting on a Double NAT, and the ISP router is still unnecessarily processing traffic.

The only correct way to set up a third-party mesh system is Bridge Mode, which turns the ISP router into a dumb pipe and lets your mesh system do 100% of the heavy lifting. Airtel grays this option out in their Sercomm routers. Customer support often refuses to enable it.

Here is how you can bypass the lockdown and do it yourself without their help.

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Prerequisites

Before we start, you need two things:

1. A laptop or desktop using Google Chrome.
2. Your router physically connected to your computer via Ethernet or Wi-Fi.

Step 1: Extract Your Hidden PPPoE Password

To bypass the Airtel router, your Deco mesh needs to securely log into Airtel’s servers itself. You will need your PPPoE Username and Password. If you don’t know it, you can extract it right from the router interface.

1. Log into your Airtel Sercomm router’s web interface (usually 192.168.1.1).
2. Navigate to the WAN Connection List and select your active internet profile (often named something like 1_TR069_INTERNET_R).
3. You will see your PPPoE Username, but the Password will be hidden by dots.
4. The Hacker Trick: Right-click directly on the password box and select Inspect. A developer tools panel will open on the side of your screen.
5. Look for the line of code highlighted in blue. Find the part that says type="password".
6. Double-click the word password, type text instead, and press Enter.
7. You will now be able to see Password. Note it down.
8. Look for VLAN ID and note it down. It is usually 100.

The dots will instantly reveal your real password. Copy both the Username and Password down as you will need them in a few minutes to put it on the other router (Deco in my case).

Step 2: The Bypass – Forcing Bridge Mode

Now, we need to unlock the grayed-out settings on that exact same page.

1. On the WAN connection page, look for WAN Connection List and it should say, 1_TR069_INTERNET_R
2. You can go ahead and click on it for other options. You should now see 5_OTHER…, you can select this.
3. This is a Bridge Mode profile already created for LAN1. Hence, I will connect my Main Deco to my Airtel Fiber Router via LAN 1.
4. You will now be able to see Enable/Disable which will be unticked and grayed out.
5. Right-click the grayed-out dropdown box and click Inspect.
6. In the highlighted code, look for the word disabled (it usually looks like disabled="disabled").
7. Delete that entire disabled attribute and press Enter. The tick option will now be magically enabled.
8. Tick it and it should be enabled.
9. Do the same for the SAVE button at the bottom and click on SAVE button to apply the settings.

Don’t panic: The internet light on your Airtel router will go out, and your connection will drop. This is exactly what you want. The Sercomm is now a lobotomized “dumb pipe.”

Step 3: Configure Your TP-Link Deco

Now we pass the baton to the mesh network. Note that if you are trying to connect other router of your choice, the settings might differ. Browse around and you should find the settings.

1. Plug your primary Deco node directly into LAN1 on the back of the Airtel router using an Ethernet cable.
2. Open the Deco app on your phone.
3. Go to More > Internet Connection.
4. Change the connection type (usually set to Dynamic IP) to PPPoE.
5. Enter the Airtel Username and Password you extracted in Step 1 and hit Save.
6. Next, go back to More > Advanced > IPTV/VLAN.
7. Toggle it On, set the ISP Profile to Custom, and enter 100 into the Internet VLAN ID field. (Leave the priority at 0).
8. Hit Save.

Step 4: Shut Off the Noise

There is one final housekeeping step. Because your Deco is now handling all of your home’s Wi-Fi, you need to stop the Airtel router from broadcasting its own signal.

Log back into the Airtel router interface and completely disable the SSID broadcast for both the 2.4GHz and 5GHz bands. Leaving them on will only crowd the wireless channels, cause interference, and slow down your Deco network.

The Result

Once your Deco reboots, it will authenticate directly with Airtel’s servers. The LED will turn solid, and your internet will come back online.

You now have a true Bridge Mode setup. Your Deco X10 and M4s are handling all IP assignments, firewall security, and routing across all three floors, completely free of Double NAT limitations!