Accessing the Dropbox site disables my internet connection

Hi everyone!

Thanks for reporting this to the Community.

I have actually been collecting all of the reports of this across the community and and Reddit as well, to put together a cohesive report for our internal team. This is now being looked into and hopefully we will have a fix soon.

In the meantime, here is the results of some of our investigations and steps you can take:

Avast

At this time, we are not certain of the feature causing the problem. We suspect Web Control, which includes a Business feature tier, although it might be the Firewall feature.

The Web Control feature enforces domain-level blocking across categories such as “Business,” “Cloud Storage,” or custom groups, per Avast. As Dropbox is a Cloud Storage provider, this suggests a whitelist for approved services in a Business environment is assumed by Avast.

Here are Dropbox’s official domains:What official domains does Dropbox use?

We have contacted Avast support, are investigating how we might reproduce this problem, and we’d appreciate any feedback on the results of this set of steps:

Troubleshooting Steps

1. Open the Avast dashboard and check the Notifications log for URL: entries.
2. Disable one protection component at a time to isolate the trigger (Web Shield, Real Site, Firewall).
3. Add the affected domain to Exceptions (enter the base domain, such as example.com, not just a page).​
4. Restart your browser and re-test.

Additional items to check:

Firewall rules are managed under Protection → Firewall → Apps or Network Rules → Unblock or Allow connection.

Avast’s Real Site feature overrides your system DNS to prevent DNS hijacking attacks. Disabling or excluding the dropbox.com domain from Real Site may restore connectivity.

If the issue is primarily happening while working with the Desktop application, Avast documentation indicates that Behavior Shield can block background components of web-based apps if they install supplementary local services, and Email Shield can block webmail plug-ins or APIs invoked by desktop clients.

Norton

At this time, we are not certain of the feature causing the problem, but we suspect firewall related settings, or the Intrusion Prevention System features.

Norton's Smart Firewall feature actively filters all inbound and outbound network traffic and can block domains or disconnect Wi-Fi in certain configurations.

Norton 360 includes a VPN and Wi‑Fi inspection engine that monitors unsecured networks. These features can interrupt network sessions or override local DNS settings, mimicking a Wi-Fi disconnect symptom. Norton recommends whitelisting your trusted network under Settings → VPN → Split Tunneling → Add Trusted Network (link).

Norton provides some recommended steps here and also noting that “Internet Connection Sharing” setting defaults to “Block,” which can cause Wi-Fi disconnections or “no Internet access” errors until toggled to “Allow” (link included screenshots). Adjustments can be made under Settings → Firewall → Program Rules or Network Trust Configuration.

If you are experiencing issues primarily through the Dropbox Desktop application, Norton’s Intrusion Prevention System feature looks similar to a known issue with ESET’s HIPS feature (actively in progress to fix).

Norton performs deep packet inspection on HTTPS traffic, issuing its own root certificate to decrypt and inspect it. If you are seeing “Secure Connection Failed” or “Privacy Error” or ‘socket’ errors in your browser, this feature could be the issue. You can temporarily disable this feature to confirm under Web Protection → Encrypted Connections → Disable HTTPS Scanning.

We have contacted Norton support, are investigating how we might reproduce this problem, and we’d appreciate any feedback on the results of this set of steps:

Troubleshooting Steps

1. Open Norton Dashboard → Device Security → Settings → Firewall → Intrusion and Browser Protection.
2. Disable one module at a time (Firewall, SSL Scanning, Safe Web, VPN) and retry Dropbox.
3. Review the Security History logs under “Web Protection” for blocked domain events.
4. Add permanent exceptions under Web Protection → Exceptions → Add Web Address.

Here is a list of all domains used by Dropbox for reference: What official domains does Dropbox use?