@rajesh176 

This looks like an issue from an old thread - here.

The only way to be sure that this is a FW issue is to do the following:

1. Make notes about your router configuration (for example in Notepad).

2. Create a router configuration backup file using the Backup feature.

3. Hard reset the router using the reset button on the back panel (hold it for about 10 seconds).

4. Instead restoring from a backup file - configure the router from scratch (only basic settings) using your notes (from step 1).

5. Test and check if there's any improvement. If there is - make sure you have restored all previous settings from your notes and stop here.

6. If there's no improvement you can restore the router configuration from the backup file (from step 2) using the Restore feature.