Try this link - https://turbotax.intuit.com/irs-tax-extensions/
Or try a different browser.
IRS extension link - https://www.irs.gov/forms-pubs/extension-of-time-to-file-your-tax-return
If you are getting a refund, don't sweat the extension. If you owe, make a payment. Pay your taxes at IRS Direct Pay (this also automatically gives you an extension).
If you have to, change the time and date settings on your computer to reflect a west coast time zone if it is a timing issue.