It seems unlikely on the face if it as RTRR has you specify by LAN ip address for remote server at least but good to know the facts or how to make it work.
regards
SMB and rsync are different protocols. Nothing to-do with each other.
Hmmm, I took it that RSYNC and RTRR were shell programs running on top of other protocols to transfer the data. This is not the case?
regards
That’s correct, they’re not (although RTRR is a QNAP invention, and is a bit of a black-box, so only QNAP can say exactly how it works).
But neither have anything to-do with SMB, which is for file-sharing.
Hmm All QNAP say is that “Real-time Remote Replication (RTRR) is a proprietary backup method built into QNAP NAS devices that can create incremental data backups. RTRR improves backup efficiency and reduces backup time.
Configuring the RTRR server on a NAS allows the NAS to become a target in a backup or sync job using the RTRR protocol.”
I thought this was file sharing?
No, RTRR is not file-sharing. It’s for file replication. It’s generally used to backup files.
That is really unfortunate. I use HBS to backup NAS to NAS and the one time I really want fast data transfer is when doing these large backups which can run to a few TBs especially when first running. It seems bizarre that QNAP would not enable some kind of multi channel support in this case.
SMBM is a bit of a workaround.
If you really need speed, use faster NICs. 
I Wish 
, The TVS-h674 only comes with 2 x2.5Gbe connectors, and though it has 2 PCIe slots, when you drop in a GPU there go both slots. My other local NAS has no PCIe slots but multiple ports.
And you really would think that if QNAP are going to spruik SMB multi channel they could put their own house in order first and make sure it uses all channels available for connection on its proprietary HBS back up software otherwise you may as well just transfer files across normally.
/rant off
SMBM has its uses, but rsync isn’t one of them.
Use the right tools for the job.
Don’t cheap-out on hardware. If you want performance, it costs. I know, your NAS model costs a bundle, but it clearly can’t do what you want.
QNAP have never claimed this model can do more than it does. You thought it could, because you didn’t understand how rsync works. That is not QNAP’s fault. Try to not foist your expectations on the manufacturer.
That was not helpful.
It’s far-more helpful than a rant. 
Even if you were able to use multi-channel, it still might not speed up your transfers that much. People think, “If I have a 10 Gbit connection, then my data transfers will run at 10 Gbit.” Well, not really. Data transfer speeds of any type (SMB, RTRR, etc) are affected by multiple things. First is the fact that the file needs to be read/cached from the local drive, processed and then transferred. When you have a lot of very small files, yes, they transfer fast, but the time needed to do all the overhead work so that you can transfer the data dominates everything. And because the file is small, you will never see high transfer rates. When files are large, you will see the transfer rates go up and that is because there’s no additional overhead going on than just transferring the file. Most files are small and so you’ll never really fully utilize a 5 or 10 Gbit connection on average. This is just the way it is with any system. Doesn’t matter if you have a few TB of data. If they are all kB or even MB size files, the transfer will just take a very long time.
Patience is needed when dealing with a NAS with large drive sizes and large amounts of data. Transfers and backups just take time.
For example, I back up my Time Machine backups weekly to a USB 3.0 drive. Should be plenty fast to transfer data - right? I have just over 8 TB of data. Yesterday’s job started at midnight. It finished at 7 PM. That’s 19 hours and that is over a locally connected USB 3.0 drive with plenty of bandwidth. But Time Machine backups have a large number of smallish files. It is what it is.
Could you please let us know the model of the other NAS you mentioned? Does it also use a 2.5GbE port?
Also, what is the network speed in your environment? Thank you!