Tunnel closed. packet_write_wait: Connection to UNKNOWN port 0: Broken pipe

Hello community for several days I am having problems to keep connected to a ssh tunnel that I perform to a VPS. After 2 to 4 minutes, I get this error: Tunnel closed. packet_write_wait: Connection to UNKNOWN port 0: Broken pipe. I have been reading in forums but I still can not find a solution, these are my configuration files. It is worth mentioning that I access the internet through a proxy (Squid).

On my SSH server (/etc/ssh/sshd_config) add this lines:

ClientAliveInterval 60
ClientAliveCountMax 5
TCPKeepAlive no

On my SSH client (~/.ssh/config):

Host myhost
    User root
    ProxyCommand proxytunnel -p proxy.example.com:3128 -P userproxy:passwordproxy -d dominiovps.com:443 -v -H "User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Win32)" 
    ServerAliveInterval 60
    ServerAliveCountMax 5
    TCPKeepAlive no

Try to decrease ServerAliveInterval to 15 or 20: looks like your proxy server is configured for timeout lower than 60 and closes your connection after some idle interval.