ssh偶而不能登錄問題

我的ssh主機常常過了一段時間.大約是5-7天..我要連線就會失敗.
OpenSSH_3.1p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
debug1: packet_send2: adding 64 (len 60 padlen 4 extra_pad 64)
debug1: ssh-userauth2 successful: method password
debug1: channel 0: new [client-session]
debug1: send channel open 0
debug1: Entering interactive session.
debug1: channel_free: channel 0: client-session, nchannels 1
Connection to [url]www.test.com.tw[/url] closed by remote host.
Connection to [url]www.test.com.tw[/url] closed.
debug1: Transferred: stdin 0, stdout 0, stderr 97 bytes in 0.0 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 50417.1
debug1: Exit status -1

然後過了大約20分鐘.在試就又可以正常連線了...
不知為何,可以請各位大大提供一點意見看看問題再拿裡嗎??