"connection.gateway-ping-timeout: cannot set property: value of "###" of type 'guint' is invalid or out of range for property type 'gateway-ping-timeout' of type 'guint' "
"###" is sometimes a different value and sometimes repeating.
Also reported here
Found a bug report here
This is new to 16.04. If a fix is not available, a workaround would help too.