Hello, before you proceed on the instruction please check first the product version since this is more accurate in version 8.0.35.

link-load balancing route can be used to prevent wasting bandwidth.

There are four types of policy for link-load balancing as follows:

Requirements: All internal network users will go to the external network through
eth1. The method being chosen here is Prefer Link at Top.
Configuration:
Step 1. Fill in the policy name (Any will do)
Step 2. Source Zone (where the internal network user is located)
Step 3. Source IP (All)
Step 4. Destination IP group (All)

Step 5. Select HTTP application in the Application
Step 6. Interface (Select eth1 and eth3)
Step 7. Others can be kept as default Sample Configuration:

I hope you did it right.

Link load-balancing route

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Outbound Interface เลือก Interface ขา Wan หรือ Link internet เข้ามา

Add Interface

Mode load-balancing

Route

Enable Link state Detection ที่ static route ขา WAN

Interface

Enable Link state Detection

Configuration Step:
Step 1. Fill in the policy name (Any will do)
Step 2. Source Zone (where the internal network user is located/LAN)
Step 3. Source IP (All)
Step 4. Destination IP group (All/ANY/WAN)
Step 5. Select HTTP application in the Application
Step 6. Interface (Select eth1 and eth 3/WAN

Step 1. Fill in the policy name (Any will do)
Step 2. Source Zone (where the internal network user is located)
Step 3. Source IP (All)
Step 4. Destination IP group (All)
Step 5. Select HTTP application in the Application
Step 6. Interface (Select eth1 and eth 3
Step 7. Others can be kept as default Sample Configuration

Step 1. Name of the policy, please (Any will do)
Step 2. Source Area (where the internal network user is located)
Step 3. IP source (All)
Step 4. Destination IP assortment (All)
Step 5. In the Application, choose HTTP application.
Step 6. (Choose eth1 and eth 3 for the interface.
Step 7: The remaining items can be left in their normal configuration

Please check the product version before continuing with the instructions because they are more accurate in version 8.0.35.
To avoid wasting bandwidth, employ the link-load balancing route.

Network >Route>Policy Based Route and configure your desire route

Configuration:
1) Enter the policy name (Any will do)
2) Zone of Origin (where the internal network user is located)
3) IP address of origin (All)
4) Group of destination IP addresses (All)
5) In the Application menu, select HTTP application.
6) Interaction (Select eth1 and eth2)
Others can be left as the default.

thank you colleagues