Can't connect to partner anymore (Win 10)

On 10 PCs I'm using TeamViewerQS. However, since very recently I can't take over one PC anymore. Sometimes it takes around 5 minutes for getting access. When I try to remote access one of the PCs, the 'client' will go offline (the whole internet). This will take up to ~5 minutes, and as soon as the PC gets back online, it will automatically take it over... When I try again, it will behave exactly the same. I've tried the following:

- Turned off 'IPv6'
- Disabled proxy
- Disabled firewall
- Removed Anti-Virus
- Reinstalled TeamViewer completely
- Pinging to 'router12.teamviewer.com' is going fine (reply)
- Tried to use TeamViewer instead of TeamViewerQS

And this is what I can find in the log file:

2019/08/31 00:46:45.272 10608 12584 G1!!!CTcpConnectionBase[62]::HandleResolve(): Resolve failed, router9.teamviewer.com:5938, Error: system:11001
2019/08/31 00:46:45.272 10608 12584 G1! KeepAliveSessionOutgoing[router9.teamviewer.com]::ConnectEndedHandler(): State is 1
2019/08/31 00:46:45.272 10608 9816 G1! CProcessCommandHandlerKeepAlive[43]::HandleKeepAliveConnect(): Connect to KeepAliveServer failed
2019/08/31 00:46:45.272 10608 9816 G1!!!KeepAliveSessionOutgoing::ConnectFailureHandler(): KeepAliveConnect to router9.teamviewer.com failed
2019/08/31 00:46:45.272 10608 9088 G1 CKeepAliveClientClient::StartConnect(): Protocol 4 proxy -- IP router9.teamviewer.com
2019/08/31 00:46:45.273 10608 9088 G1 Activating Router carrier
2019/08/31 00:46:45.274 10608 9088 G1!! HttpRequestImpl::CurlFinished(): curl request failed: Couldn't resolve host name (6), Could not resolve host: router10.teamviewer.com
2019/08/31 00:46:45.274 10608 9088 G1!! Port443Connection::RequestFinishedCallback: failed with HTTP status code = 0
2019/08/31 00:46:45.274 10608 9088 G1! KeepAliveSessionOutgoing[router10.teamviewer.com]::ConnectEndedHandler(): State is 1
2019/08/31 00:46:45.274 10608 11696 G1! CProcessCommandHandlerKeepAlive[44]::HandleKeepAliveConnect(): Connect to KeepAliveServer failed
2019/08/31 00:46:45.274 10608 11696 G1!!!KeepAliveSessionOutgoing::ConnectFailureHandler(): KeepAliveConnect to router10.teamviewer.com failed
2019/08/31 00:46:45.274 10608 9816 G1 CKeepAliveClientClient::StartConnect(): Protocol 2 proxy -- IP router10.teamviewer.com
2019/08/31 00:46:45.275 10608 9816 G1 Activating Router carrier
2019/08/31 00:46:45.276 10608 11696 G1!! HttpRequestImpl::CurlFinished(): curl request failed: Couldn't resolve host name (6), Could not resolve host: router2.teamviewer.com
2019/08/31 00:46:45.276 10608 11696 G1!! CHttpConnectionOutgoing::ResolveDNSName: resolving DNS name failed, status = Failed, HTTP response code = 0, URL = 'http://router2.teamviewer.com/cname.aspx'
2019/08/31 00:46:45.276 10608 11696 G1!! CHttpConnectionOutgoing::HandleResolveDNS: empty address, m_ConnectionState=0
2019/08/31 00:46:45.276 10608 12584 G1! CProcessCommandHandlerKeepAlive[45]::HandleKeepAliveConnect(): Connect to KeepAliveServer failed
2019/08/31 00:46:45.276 10608 12584 G1!!!KeepAliveSessionOutgoing::ConnectFailureHandler(): KeepAliveConnect to router2.teamviewer.com failed
2019/08/31 00:46:45.276 10608 9088 G1 CKeepAliveClientClient::StartConnect(): Protocol 1 proxy -- IP router2.teamviewer.com
2019/08/31 00:46:45.276 10608 9088 G1 Activating Router carrier
2019/08/31 00:46:45.277 10608 11696 G1!! HttpRequestImpl::CurlFinished(): curl request failed: Couldn't resolve host name (6), Could not resolve host: router6.teamviewer.com
2019/08/31 00:46:45.277 10608 11696 G1!! CHttpConnectionOutgoing::ResolveDNSName: resolving DNS name failed, status = Failed, HTTP response code = 0, URL = 'http://router6.teamviewer.com/cname.aspx'
2019/08/31 00:46:45.277 10608 11696 G1!! CHttpConnectionOutgoing::HandleResolveDNS: empty address, m_ConnectionState=0
2019/08/31 00:46:45.277 10608 9088 G1! CProcessCommandHandlerKeepAlive[46]::HandleKeepAliveConnect(): Connect to KeepAliveServer failed
2019/08/31 00:46:45.277 10608 9088 G1!!!KeepAliveSessionOutgoing::ConnectFailureHandler(): KeepAliveConnect to router6.teamviewer.com failed

I'm using the following version: 14.5.5819 QS
Windows version: 1903