I don't see a call for  wnl()   
but ancient coding practices  would suggest its:  writenewline just that
and that's what it does without any other content.
though the remark is rater direct if interpreting feedback := line

// Should be smart as well: routines ending with write ! will create an empty feedback!

just a guess:
with do content.MoveTo(content.Size - 1)   you are probably just between CR and LF 

Could you try do content.MoveTo(content.Size - 3)  just to make sure you a e before CRLF

I'm not sure how EOL is triggered
eventually also check returned success code

1)  
%Stream.GlobalBinary has a warning:

Note that on a unicode Cache although you can write unicode data into this class and read it back out this is not a supported use of this class and the Size property would be incorrect in this case as it would be the size in characters rather than the size in bytes

2)
   do content.OutputToDevice()
now your content is out and you are positioned at end

    do content.MoveTo(content.Size)
now you re-read content until LastCharacter-1, whatever total size might be
    set isNewLineTerminator = (content.Read(1) = $char(10)) 
reading the assumed last character

3)
you might be better off to use  content.ReadLine(,.sc,.eol) and check eol for the termination status

The first thing to check in Mgmt Portal is size of Global Buffers  - Rule of thumb: 50% of available RAM
http://<yourhost>:<yourport>/csp/sys/mgr/%25CSP.UI.Portal.MemoryStartup.zen

Check Cache Efficiency in System Dashboard before and after restart
http://<yourhost>:<yourport>/csp/sys/op/UtilDashboard.csp?$NAMESPACE=

Thanks Ed! 
I just went through old DC post for half an hour+ to detect it. 

It's much better than my link to Facebook. 

Regards

do you look for this one?

%ENSInstallDir%\CSP\broker\portal\EnsembleLogo210x50.png

 (in my case 192.168.56.1), whereas one would need 71.174.62.16

This means you try to get information that is stored in your router's and/or firewall's  (NAT, DHCP,... ) routing/mapping table.
I'd assume you need to use some utility of your OS using $ZF(-1,...) $ZF(-2,...) to get the outside view of the inside server

This might work inquiring nslookup on a DNS server outside your NAT, ...  Though I never tried it

Hi,
without any  REST (at that point)  as you expect to hand action from front-end to back-end:

If your front-end is able to listen on a dedicated IP port  then all you need is to send your data to the (negotiated?) IP:port.
Take a look to %Net.HttpRequest 
http://docs.intersystems.com/latest/csp/documatic/%25CSP.Documatic.cls?P...

From point of view of Caché your front-end acts then like a web-server receiving data.
Your reply from front-end  signals to Caché that the front-end is ready for the next junk / or terminates the stream

You are right. The check for pure number got lost

if  +number=number  has to precede 

so the combined is  if  +number=number,number\1=+number

The oldest and most simple and fastest integer check is
if value\1=+value

\1 strips trailing decimals,  + strips leading 0

; just pure integer arithmetics no string checks

since every installation of Caché has it's gateway I'm not clear what you did by
" configured as CSP gateway. "
with no manual change the gateway always talks to your local server  ser-app-w

From CSPgatewayMgmt on ser-app-w  you should check access to ser-app-db

The fact that the table is external  is just a concern of storage strategy in the generated Caché Class
To your COS code  it's just another class projected as table.

Use it by your preferred ResultSet Class
It might be a good idea to check access first from Mgmt Portal to verify access rights.

for the example:
http://docs.intersystems.com/latest/csp/documatic/%25CSP.Documatic.cls?P...

so you may use $$$comClassDefined(class)  for compile classes

or go for ^oddCOM(....)