How to change TTL to 65 on 4G router?

The default TTL value on the 4G router is 64. In some conditions, we need to change the TTL value to 65. The TTL parameter is controlled by /etc/sysctl.conf. We can edit the “sysctl.conf” file via SSH terminal or WinSCP software.

After connected to the 4G router, access the router admin. Go to “System > Terminal” to access the SSH interface on the web page. We can also use PuTTY software to access the SSH interface.

Input the below command and press enter to check the current TTL value. If the return value includes “TTL=64”, follow the below steps to change the TTL value.

ping -c 5 localhost

Edit TTL with VI editor on SSH Terminal

  1. Use the below command to open the configure file.
    vi /etc/sysctl.conf

  2. Find a free line, and hit “Insert” on the keyboard to edit the configure file.
    Note: On a Mac computer, use Fn+i or Fn+Command+Return to insert a new line.

  3. Add the below content on the free line.
    net.ipv4.ip_default_ttl=65

  4. Hit “ESC” on the keyboard to stop editing

  5. Input “:wq” to save the configuration file and quit the VI editor.

  6. Reboot the router

  7. Use the above “ping -c 5 localhost” command to verify the TTL value.

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