Don’t worry when you find this error in IIS log files "Timer_ConnectionIdle".
the error come when no data received within timeout period, mostly in case of web services where multiple user try to submit request, you just need to set MinFileBytesPerSec property or simply reset the IIS will solve the problem.
Here with steps that strongly recommended to resolve this issue permanently.
1) Check your connection pool defines in config file.
Kindly comment if find it helpful.