Forwarder on Coreelec;"proto.HyperionRequest" missing command

I'm using an Odroid c2, with Coreelec 20190513, and the HyperionNG addon 9.1.100.3
The Ambilight itself is working fine.
But the forwarder does not.
My configs are attached, I use the normal one for grabbing Kodi, and an Ambilight with an Arduino (which works) and want to forward it locally to two other instances of Hyperion. These two are for a left and right placed atmoorb ESP8266.
But I got the following error message

May 14 10:05:26 CoreELEC sh[2854]: [libprotobuf ERROR /var/corebuild/CoreELEC/build.CoreELEC-Amlogic.arm-9.0-devel/protobuf-3.1.0/src/google/protobuf/message_lite.cc:119] Can't parse message of type "proto.HyperionRequest" because it is missing required fields: command
May 14 10:05:26 CoreELEC sh[2854]: [hyperiond FLATBUFCONNECTION] <ERROR> Unable to parse reply
May 14 10:05:26 CoreELEC sh[2854]: [hyperiond FLATBUFCONNECTION] <ERROR> Unable to parse reply
May 14 10:05:26 CoreELEC hyperiond[2857]: Unable to parse reply
May 14 10:05:26 CoreELEC hyperiond[2857]: Unable to parse reply
May 14 10:05:26 CoreELEC sh[2854]: [libprotobuf ERROR /var/corebuild/CoreELEC/build.CoreELEC-Amlogic.arm-9.0-devel/protobuf-3.1.0/src/google/protobuf/message_lite.cc:119] Can't parse message of type "proto.HyperionRequest" because it is missing required fields: command
May 14 10:05:26 CoreELEC sh[2854]: [hyperiond FLATBUFCONNECTION] <ERROR> Unable to parse reply
May 14 10:05:26 CoreELEC sh[2854]: [hyperiond FLATBUFCONNECTION] <ERROR> Unable to parse reply
May 14 10:05:26 CoreELEC hyperiond[2857]: Unable to parse reply
May 14 10:05:26 CoreELEC hyperiond[2857]: Unable to parse reply

Is there anything I could do to fix it?

edit:
one day later, I tried the forwarder on an RPi3. A fresh Raspbian, and latest HyperionNG. Compiling works fine, but the forwarder also does not work. It's the same error:

[libprotobuf ERROR /home/pi/hyperion/dependencies/external/protobuf/src/google/protobuf/message_lite.cc:123] Can't parse message of type "proto.HyperionRequest" because it is missing required fields: command

So maybe HyperionNG is missing something...?

edit2:
I got it working.
I'm using a Proto to Flat forwarder now, and that works.
Before, I tried Proto to Proto, which gave me these errors.

So, I've got two instances of Hyperion NG running.
One as a sender, one as a receiver.
The sender has the forwarder enabled, in there is a json and a proto port.
(If you don't have that option, you need to change in Hyperion NG the settings level to expert)
On the Hyperion NG config website, go to Configuration, then Network Services. At the bottom, there's the forwarder option. Activate it and fill in the json and proto field with the IP of the receiver Hyperion NG instance. If it's on the same device, use localhost, or the actual IP. The Json and Proto port should be a different one.
If you save your config and open it, it will look like this:

"forwarder": {
        "enable": true,
        "json": [
            "192.168.1.10:19500"
        ],
        "proto": [
            "192.168.1.10:19510"
        ]
    }

The IP is from the device that should receive the data. The Json and Proto Ports can mostly be choosen freely. I'm using something above 194000.

On the reciever side, go to Configuration, Network Services. Activate the Flatbuff Server and fill the Json and Flatbuff Port with the values from above.
In this config, it will look like this:

"jsonServer": {
        "port": 19500
    },


    "flatbufServer": {
        "enable": true,
        "port": 19510,
        "timeout": 3000
    }

The Ports from the receiver match the ones from the sender.

You can do this on one device, or forward it to another device with Hyperion NG.
I'm doing both, I have 3 instances on my Odroid C2, and sometimes I forward from another Pi3 to that Odroid. Working fine^^
I hope, that helps^^

You're welcome
Hm...
You could try a few things.
Test, if forwarding hyperion ng with Proto instead of flatbuffer to old hyperion works.
If not, in coreelec there is the old hyperion as am add-on as well. But I have no idea, how good that works, or if it works at all..
Last would be, to upgrade your hyperion to hyperion ng.
I don't know if you need coreelec for that, or if libreelec works as well.
For hyperion ng, you either need to compile it yourself, like written on the github, or search this forum for a already compiled version. I think there should be something floating around.

More a general question, why do you forward the data?