This is just a WAG, but maybe you need to solidify your auth, before you try and get a channel? Also what is $ssh2-> ($chan2);?

  
#instead of
if($ssh2-> auth_password('user', 'pass')){
        print "ok";
    my $chan2 = $ssh2-> channel();
    $ssh2-> ($chan2);  #what is this step?
    print $chan2 "uname\n";
  
#try it without the if block
  $ssh2->auth_password('user','pass') or die "Unable to login $@ \n"; 
+                      
  my $chan = $ssh2->channel();                                        
+                      
  $chan->blocking(0);                                                 
+                      
  $chan->exec('ls -la');                                              
+                      
  while (<$chan>){ print }                                            
+                      
  #$chan->close;
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