Firewall not allowing delta.com

Do not disconnect or permanently disable either firewall; because only one website is affected and Avast previously resolved it, temporarily test Avast Web Shield and then create a narrow website exception only if that test identifies Avast as the blocker.

Test Avast without removing protection permanently

1. Confirm that the address is exactly https://www.delta.com.
2. Open Avast → Protection → Core Shields.
3. Temporarily turn off Web Shield/Web Guard.
4. Close and reopen the browser, then test Delta’s website.
5. Turn Web Shield back on immediately after the test.

Avast recommends this temporary test for website-access problems. If the site works only while Web Shield is off:

• Update Avast’s virus definitions and test again.
• Report the detection to Avast as a false positive.
• If you trust the address and need immediate access, add only the exact Delta URL under Menu → Settings → General → Exceptions → Add Exception. An exception reduces scanning protection, so do not exclude the entire browser or use a broad wildcard. ^1^ ^2^

If Avast Firewall—not Web Shield—is responsible, open Avast → Protection → Firewall → Apps and allow the affected browser. Check Networks as well, but mark the network Trusted only when it is your private home network, not public Wi-Fi. ^3^

Keep Windows Firewall enabled

Windows Firewall generally permits outbound web traffic unless an outbound rule explicitly blocks it. Do not open inbound ports for a website: opening ports increases exposure and does not normally resolve access to one public site. Microsoft recommends allowing an application rather than opening a port when an exception is genuinely necessary. ^4^

If Avast is not responsible:

1. Open Windows Security → Firewall & network protection.
2. Select Restore firewalls to default.
3. Confirm the reset and test again.

This removes custom Windows Firewall rules, so any legitimate rules previously added for other applications may need to be recreated. Microsoft specifically provides this reset when firewall changes cause applications to stop working. ^5^

If the site still fails, open Command Prompt as administrator and clear the DNS cache:

ipconfig /flushdns
ipconfig /release
ipconfig /renew

Then restart the browser. These commands are appropriate when one PC has the problem while other devices on the same network can reach the site. ^6^

Also test Delta in another browser and on another device using the same network. If every device fails, the PC firewalls are unlikely to be the source; restart the router or contact the network provider. If only this Windows 10 PC fails, the Avast test, DNS refresh, and Windows Firewall reset above isolate the most likely local controls.

Windows 10 reached end of support on October 14, 2025, so upgrading to Windows 11 is recommended for continuing security fixes. ^7^

References

1. Troubleshoot website access issues | Avast
2. How to exclude files or websites from scans in Avast Antivirus | Avast
3. How to allow internet access in Avast Antivirus and Avast One Firewall ...
4. Risks of Allowing Apps Through Windows Firewall | Microsoft Support
5. Firewall and network protection in the Windows Security app | Microsoft Support
6. Problems accessing banking websites - Widows 10 - Microsoft Q&A
7. Automatically fix Windows security issues | Microsoft Support