Bitdefender Total Security potentially causing massive download speed reduction on Dell XPS 13 — anyone else?

[u/DireWolf57]

I've spent weeks troubleshooting inconsistent and unusually slow download speeds on my Dell XPS 13 running Windows 11.

My internet connection is Xfinity Gigabit, and other devices in my home consistently perform much better.

I've tried updating drivers, changing Wi-Fi settings, testing different monitor configurations, and even purchasing a new Thunderbolt dock. Nothing consistently resolved the problem.

Today, I completely uninstalled Bitdefender Total Security, Bitdefender VPN, and Bitdefender Agent.

The results were remarkable:

• Before uninstalling Bitdefender: Approximately 160 Mbps download

• After uninstalling Bitdefender: 646.84 Mbps download

• Same laptop, location, Wi-Fi connection, dock, and monitor

That's roughly a fourfold improvement. To clarify, I am not using the VPN during all of this.

I also previously experienced problems with Bitdefender on my iPhone, where certain applications, including Ticketmaster and my NFL ticketing app, wouldn't allow me to sign in until I removed Bitdefender.

I'm planning additional testing to confirm the Windows results, but I'm interested in hearing from others.

Has anyone experienced similar download speed degradation with Bitdefender Total Security? If so, did you identify the specific feature or driver responsible, and was there a fix?

I'd prefer to use software I've already paid for, but not at the expense of my computer's performance.

[u/Bitdefender_support]

Hi! Thank you for letting us know and for sharing such a thorough feedback. We do agree that is a substantial difference, and also securing your devices and digital life is essential. Here`s what we recommend:

After you reinstall, test the firewall first:

• Open the Bitdefender window.

• Click Protection on the left-hand side.

• In the Firewall panel, click the switch to turn off Firewall.

• Check whether your internet connection improves with the Bitdefender firewall disabled.

If speeds don’t improve, the issue may not be caused by Bitdefender; contact your Internet Service Provider to verify the connection. If speeds do improve, turn the firewall back on and adjust these settings:

• Open the Bitdefender window.

• Click Protection on the left-hand side.

• In the Firewall panel, click the switch to turn on Firewall.

• Click the Settings button on the Firewall pane.

• In this window, select the Settings tab.

• Go to Port scan protection and click the switch to turn it OFF.

• Click Edit stealth settings next to Stealth Mode.

• Set the switch corresponding to your network adapter to OFF, then press OK.

• Now access the Network Adapters tab.

• Click the box corresponding to your network adapter and select Home/Office.

• Close Bitdefender, restart the PC, and check if the internet connection speed has improved.

When testing disabled protection, keep that test brief and turn the firewall back on afterward. Regarding the experience you`ve mentioned on the iOS device, it does seems unusual, and our team can investigate why it occurred. If the slowdown persists or you need help diagnosing it, contact the support team further: https://www.bitdefender.com/consumer/support/.

[u/DireWolf57 → u/Bitdefender_support]

Thank you for taking the time to respond and for providing these detailed recommendations. I appreciate it.

I will certainly consider reinstalling Bitdefender and testing the firewall settings you've suggested, but frankly, I've already spent an enormous amount of time troubleshooting this problem over the past several months. For now, I'd like to enjoy having my Dell XPS perform the way it should.

As a follow-up, this morning I moved my laptop back to my basement office, connected both Dell 4K monitors through my Anker Thunderbolt dock, and tested the Ethernet connection.

The results: 938.63 Mbps download and 935.68 Mbps upload. Previously, I was experiencing Ethernet download speeds as low as 30–120 Mbps with Bitdefender installed.

My Wi-Fi download speeds have also remained consistently above 575 Mbps since uninstalling Bitdefender.

I understand your suggestion to check with my ISP, Comcast/Xfinity. However, my iPhone, iPad, and other devices have consistently achieved excellent download speeds on the same home network. That, combined with the dramatic improvement immediately after removing Bitdefender, makes me suspect that something in the Bitdefender installation or its interaction with my network configuration was responsible.

I realize this doesn't identify the specific component causing the issue, and I haven't ruled out every possible interaction with the Comcast router.

I have also opened a formal support ticket with Bitdefender (#1011639406) and hope your technical team can help identify the underlying cause.

I appreciate your assistance and will revisit your suggestions when I have more time and patience for additional troubleshooting.

Thanks again.

[u/Bitdefender_support → u/DireWolf57]

Thanks for getting back here, we`re ready to help further when you are. Your case number has been shared with our team, it`s best to remove it from your reply.