Perspective No Gateway Connection

Ignition Version : 8.1.23

We found the issue this week. Ignition Perspective App can't connect to scada server but other scada project works at same time. We did ping test for this device, the device was connected. Finally, I reboot scada gateway server, the app connect to gateway immediately. But I didn't find any error log for this issue. Did you have same experience of perspective before? or I have to adjust setting for scada server. ex Gateway Network Settings

Error message as below,

Hi All,
For your reference, I adjusted "acceptCount"(Gateway.xml) from 100 to 250. The issue be resolved, but I'm not sure it is root cause or not.