Click on below link to open Pin to Pin Distance Search Page on GST portal
https://ewaybillgst.gov.in/Others/P2PDistance.aspx

Step 1 :- Enter the “Dispatch From” and “Ship To” Pincode, then enter the captcha and click ‘Go’ button

It will show the approximate distance between that two pincodes

You have to update this distance in your customer detail

This will fix pin to pin distance error while generating E-Way bill.