RZ70 - unable to send data to SLD

Dear Experts,

we've been fighting with a nasty issue for a couple of days. After a LOT of googling, we are still stuck. There are only unclear discussions with fuzzy explanations and broken links to other discussions. So...

We are trying to connect an ABAP System - NetWeaver 7.4 SPS08 to SLD and send there the data through RZ70. On other systems (SPS15), there is a second section in RZ70, where you can directly select which RFC destination to use. However in SPS08 there is no such thing.

Even though we've configured SLDAPICUST correctly, RZ70 keeps giving an error:

Used RFC destination: SLD_UC
RFC call failed: Error when opening an RFC connection (CPIC-CALL: 'ThSAPOCMINIT', communication r

Looks like it needs registration with rfcexec. Fine !!! But how ?!? Nobody says what to run on which host specifically !!!!

I have tried on the Managed system:

rfcexec -t -a SLD_UC -g <hostname_managed_system> -x sapgw00 -> this one hangs

rfcexec -t -a SLD_UC -g <hostname_of_solman> -x sapgw00 -> this one keeps scrolling the following error:

LOCATION SAP-Gateway on host <hostname_of_solman> / sapgw00
ERROR registration of tp SLD_UC from host <hostname_managed_system> not allowed

Is this the correct location to try that ? Or I should try it on the solman host ?

I've also found that I have to set gw/acl_mode to 0. I did that on both hosts and it didn't help. However I only did a hard shutdown from SMGW on the Solman. I am afraid to do it on the other host in order to not disconnect someone working there. Please advise on what to do and ALWAYS specify on which host the corresponding action should be executed.

MANY thanks in advance!