Current update of F-Secure causes problems with udp communication

Shelin · March 27

Hi,

i use a VR Headset Meta Quest Pro with steam as PCVR, with streamer steamlink, trying to play VRChat with Face- and Eyetracking via VRCFT software. Communication between the affected modules runs between udp-port 9015/9016 and 9000/9001. But with an update of F-Secure about one or two weeks ago, FT/ET no longer works as intented. The source of the problem is F-Secure, the moment F-Surce is uninstalled, FT/ET run as intended. Somehow, F-Secure messes up teh communication there….

In a discussion within the VRCFT discord channel, it seems that more users have the same problem, rooting back to F-Secure. Just deactivating stuff in F-Secure does not work. Someone mentioned problems with multicast, idk. Is this being worked on or even a known problem? And where can i write an offical ticket for that?

I just renewed my licence, so it is very annoying that i cannot use F-Secure at the moment….

BR

Bernd

Ville · March 28

This is not a known issue. Since we don't have that hardware we can't really reproduce the problem here and would need your help to troubleshoot it.

Please follow these steps:

Open Settings / Support and turn on debug logging
Reproduce the problem with VRChat
Run F-Secure support tool
Send the fsdiag.zip that it creates to me in private message

I will open a ticket for our team and we will investigate.

Shelin · March 28

Got the file, but wtf how can I write a private message to you?

TVC15 · March 28

https://community.f-secure.com/en/discussion/comment/140388#Comment_140388

At least this is how it worked for me. Click on Ville's avatar, and you should get the option to message him.

Shelin · March 28

Havent got that option….

TVC15 · March 28

https://community.f-secure.com/en/discussion/comment/140390#Comment_140390

If you click View Profile, are you able to get this?

Otherwise, @Ville could you follow-up with this, please? TIA :)

Shelin · March 28

No, cant do nothing….I ll wait….

Ville · March 31

I have asked @Firmy as community manager to help with this issue - I don't know why you can't send private message.

Shelin · April 1

Any progress yet ? I mean at some point it would be nice to at least know that you work on the issue, which seems not possible if i am not even able to provide the data…..And i cannot use you product at the moment as well, sooo….

jk4k · April 6

Hi,

I have the same issue with F-Secure 25.2 update. I have a Windows 10 computer where I have two software communicating with each other using UDP (server IP 127.0.0.1 and port 2237). After the F-Secure updated itself to version 25.2, the communication between those two software stopped. I tried to disable Defender firewall and also temporarily disable F-Secure automatic scanning. No results, UDP communication was still not working. I checked that there was no apps in blocked or quarantine in F-Secure.

Finally I uninstalled F-Secure. After that, the UDP communication returned back normally and those two software worked as before the F-Secure update. It seems that version 25.2 somehow blocks the UDP.

BR,

Jarmo

Shelin · April 6

I also had to deinstall, because otherwise i cannot work. This is not very satisfiing and nobody here cares about that…..

Firmy · April 9

Hello @Shelin @jk4k

Thank you for your question and comment.

We regret to hear that you are facing this issue.

Could you please confirm if you have the latest version of the F-Secure app, version 25.3, installed? [Windows] What's new in the F-Secure app. Kindly ensure the app is updated and try testing again. If the issue persists, please let us know. I will send you a private message to collect a debug log for further investigation.

Thank you, and have a lovely day.

Shelin · April 10

Hi,

no, i havent had the current version because its new and I had F-Secure uninstalled, because i am not able to work otherwise. But I just tried with the new version and there is no change for me. It still blocks/messes up communication, so i had to uninstall it again.

Defender does a good job as well for me at the moment, so no rush….

Firmy · April 10

Hello @Shelin

Thank you for getting back to us.

As previously requested by @Ville, we kindly ask that you enable debug logging and generate an fsdiag file to help us investigate the issue further. Please follow the steps below:

Open Settings > Support and turn on debug logging.
Reproduce the issue with VRChat.
Run the F-Secure support tool.
Send the generated fsdiag.zip file to me via private message.

I’ve sent you a private message with further instructions. Please share the fsdiag with us privately.

Thank you, and have a lovely day.

jk4k · April 10

Hi,

I have the same problem with both versions 25.2 and 25.3. Currently, I have Fsecure uninstalled because the software prevents the use of my computer for the intended purpose.

Ville · April 10

We have tried to reproduce this problem but we can't reproduce it so far.

Could you test if stopping our network filtering driver fixes the issue.

Once the product is installed, do these steps:

Open command prompt as administrator (elevated)
Run: net stop fsnethoster
Run: net stop fsnifdrv
Run: net start fsnethoster

This disables network filtering on driver level while keeping browser extensions working. Especially banking protection is pretty useless without driver.

Let me know if this fixes the issue.

To return back to normal operating mode you can just reboot or run: net start fsnifdrv

Shelin · April 11

With fsnethoster down and fsnifdrv down, it works for me. I will send you the diag-file.

Ville · April 11

I really need to know the situation with fsnethoster up and fsnifdrv down. Can you still check that.

Shelin · April 12

Following the Test Spec

Run: net stop fsnethoster
Run: net stop fsnifdrv
Run: net start fsnethoster

It works for me

Shelin · April 17

So…..Its been three weeks since the problem was brought to your attention, a week until the source of the problem should have been identified according to the tests above. I havent seen any solution to the problem. Do you even plan, to fix that at one point in the future ? Or has it been fixed ? I do not see, have not installed it anymore,for obvious reasons. Because i am waiting for a new release and the fitting change-note.

I mean, dont get me wrong, but if you are not capable of fixing those problems in an accaptable timeframe, what the hell should i expect about the rest of your products functionality ?

Ville · April 17

While we know it has something to do with that component we are still unable to reproduce the problem. It is being worked on and it is the top priority item right now.

jk4k · April 17

I have also run those three "net"-commands and my problem vanished i.e. the UDP communication was again possible. Still, there was a weird behaviour. After I booted my computer, the UDP communication was still possible without running those "net"-commands. This continued for a few days. Yesterday when I started my computer the problem was there again. After running again those "net"-commands, the problem vanished. Currently, after the reboot, I have to execute those three "net"-commands. My setup has been the same all the time and no other software but F-Secure has been updated.

Firmy · April 21

Hello @Shelin

Thank you for taking the time to share the diagnostic log with us. We have received it.

We truly regret the disruption this issue has caused, especially considering how critical this setup is for your work and VR experience. The information you've provided has been very helpful in narrowing down the root cause.

While we’re still working on a resolution, we will make sure to inform you as soon as a fix is available. We completely understand your frustration and appreciate your patience as we work towards a solution that restores full functionality without needing to uninstall F-Secure.

If there’s anything else you'd like to share in the meantime or if anything changes on your end, feel free to reach out.

Thanks again for your understanding and support.

Firmy · April 22

Hello @Shelin @jk4k

Here’s an update on the UDP communication issue.

Our team is actively investigating the problem. Several users have found that UDP communication between local applications (e.g. ENet-based tools, SteamLink, VRCFT) fails when F-Secure is installed, and resumes once the filtering driver is stopped or the product is uninstalled.

While we work on a permanent fix, the following steps can be used to restore UDP functionality:

Open Command Prompt as Administrator
Run this command

net stop fsnethoster

net stop fsnifdrv

net start fsnethoster

This has been effective for multiple users while we continue our investigation. We’ll provide further updates here as soon as more information or a fix is available.

Thank you again for your patience and the detailed reports.

Current update of F-Secure causes problems with udp communication

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