Connection closes after about 25 seconds

I was able to establish a connection for a very long time, but it then suddenly stopped working. The connection is established, but no data is received. The connection then closes after about 25 seconds.

I noticed the following in the fortitray log which only appear after the time it stopped working:

[2026-04-30 07:21:32.5496135 UTC+02:00] [17640:15916] [sslvpnlib  510   error] [ERROR]SslvpnAgent: Pipe is broken for writing. Error=233

[2026-04-30 07:21:32.5532904 UTC+02:00] [17640:15916] [sslvpnlib  510   error] DoSendSslvpnReq() failed. Need to restart Pipe.
[2026-04-30 07:21:32.5534866 UTC+02:00] [17640:15916] [sslvpnlib  510   error] Failed to connect to SslvpnDaemon, LastError=2

[2026-04-30 07:21:32.5535905 UTC+02:00] [17640:15916] [sslvpnlib  510   error] CSslvpnAgent::SendSslvpnReq() 447 InitPipeHandle() failed.
[2026-04-30 07:21:32.5537786 UTC+02:00] [17640:15916] [sslvpnlib  1261   error] CSslvpnBase::UpdateFortiSslvpnStatus() GetSslvpnStatus() failed.
[2026-04-30 07:21:32.5538736 UTC+02:00] [17640:15916] [sslvpnlib  6016   error] 6016 UpdateFortiSslvpnStatus failed.
[2026-04-30 07:21:34.5591189 UTC+02:00] [17640:15916] [sslvpnlib  510   error] [ERROR]SslvpnAgent: Pipe is broken for writing. Error=6

[2026-04-30 07:21:34.5594969 UTC+02:00] [17640:15916] [sslvpnlib  510   error] DoSendSslvpnReq() failed. Need to restart Pipe.
[2026-04-30 07:21:34.5600286 UTC+02:00] [17640:15916] [sslvpnlib  510   error] Failed to connect to SslvpnDaemon, LastError=2

[2026-04-30 07:21:34.5603076 UTC+02:00] [17640:15916] [sslvpnlib  510   error] CSslvpnAgent::SendSslvpnReq() 447 InitPipeHandle() failed.
[2026-04-30 07:21:34.5604960 UTC+02:00] [17640:15916] [sslvpnlib  1261   error] CSslvpnBase::UpdateFortiSslvpnStatus() GetSslvpnStatus() failed.
[2026-04-30 07:21:34.5606741 UTC+02:00] [17640:15916] [sslvpnlib  6016   error] 6016 UpdateFortiSslvpnStatus failed.
 

I am using VPN Client 7.4.3.4726

The problem only appears on my working laptop which is controlled by my company. On my private laptop the connection is stable and usable. I am suspecting ZScaler to be the problem, but I was not able yet to check this, so I wanted to know if anybody has any suggestion on what to search for?

I already uninstalled and reinstalled Forti Client, I tried an older version but the problem is still the same.