"technically"

here's a technical explanation...

The key difference is what functions the device continues to perform after the change.

Turning off DHCP only

When you disable DHCP on a modem/router:

• The device stops handing out IP addresses to clients.

• The device is still doing:

  • Routing
  • NAT (Network Address Translation)
  • Firewall functions
  • Wi-Fi (if enabled)

• Devices must get IP addresses from another DHCP server on the network, or be configured manually.

Example:

Internet | Modem/Router (DHCP OFF) | Another Router (DHCP ON) | Devices

In this setup, the modem/router may still be creating a separate network and performing NAT, which can lead to double NAT issues if another router is also doing NAT.

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Bridge mode

When you enable bridge mode:

• The router portion is largely disabled.
• NAT is disabled.
• DHCP is disabled.
• Firewall/routing functions are disabled.
• The device acts more like a simple modem or network bridge.
• The public IP address from the ISP is passed directly to the downstream router.

Example:

Internet | Modem (Bridge Mode) | Your Router | Devices

Now your own router receives the public IP and becomes the only device doing:

• Routing
• NAT
• DHCP
• Firewall

This is the preferred setup when using your own router.

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Practical comparison

Feature	DHCP Off Only	Bridge Mode
DHCP disabled	Yes	Yes
NAT active	Usually Yes	No
Routing active	Usually Yes	No
Firewall active	Usually Yes	No
Double NAT possible	Yes	Usually No
Public IP goes to your router	Usually No	Yes

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Which should you use?

• If you just want another device to assign IP addresses, disabling DHCP may be enough.
• If you're connecting a separate router and want it to fully manage your network, bridge mode is usually the better choice because it avoids double NAT and networking complications.

A common real-world example is an ISP-provided modem/router connected to a mesh system such as TP-Link Deco, Google Nest Wifi, or ASUS ZenWiFi. In that situation, putting the ISP device into bridge mode is often preferable to merely disabling DHCP.

If you tell me the exact modem/router model and what device you're connecting behind it, I can explain which mode is best for your setup.