Unable to Ping stably between clients

I set up a private network, including three clients, two windows systems and one CentOS 7 (ECS). When there is a small amount of network communication, Ping communication between clients is normal. If two windows clients copy files through SMB, WinA cannot Ping WinB intermittently. At this time, the Ping between WinA and CentOS is normal, and the Ping between WinB and CentOS is also normal. The problem continued until I restarted WinA 's ZT service. After copying the file again, the problem reappears.

In addition, I temporarily added another CentOS system for testing. The large file transfer between the two CentOS clients only increased the delay, but there was no Ping interruption.

Does ZT have a log system so that I can trace problems?

After consulting the information, I found that the network interruption caused by a large number of file transfers may be related to the Qos restriction of the network provider.
Then another question arises, whether ZTO can force the use of TCP ports for communication. According to my observation, even MOON communication will still use UDP unless the TCP fallback condition is triggered.
Since I am in a network environment with strict Qos restrictions and need to use TCP for transmission, is there a good way, thanks

Hi @187353243,

I’m not aware that it’s possible to force TCP. Depending on what other traffic you have on the device, you might be able to force this by dropping udp in the local firewall. Just make sure stuff like DNS is still able to pass.