Synology to QNAP with Link Aggregation

I was trying to improve my RSYNC copy speed from Synology 1515+ to my QNAP TVX672XT by enabling Link Aggregation of all 4 ports on the Synology so that I can get the most out of my 10 Gigabit connection with the QNAP and the Netgear GS110EMX. This is a video on how I set it up.
I was hoping to get 4x the speed from the Synology to my QNAP TVS672XT with RSYNC. In any case, at least the LAG works on the Synology and hope that helps with your setup. This was a 1 time process. Now that I have the QNAP TVS-672xt connected to the QNAP TVS-472XT via 10 Gibabit, I get over 800 MB/s! Much happier with my QNAP setup.
I replaced the Synology 1515+: amzn.to/2Lv2iG9
with these
QNAP TVS-672XT: amzn.to/2k1FcMF
QNAP TVS-472XT: amzn.to/2k1CqqH
Netgear GS110EMX: amzn.to/33VxFjq
Found this answer on Reddit:
So link aggregation is an unfortunate name... TLDR: It's no faster with LAG
What link aggregation does is aggregate physical links to be one logical link. What it doesn't do is aggregate the bandwidth of those links to one big pipe.
For transfer purposes what actually happens is that the device uses a hashing algorithm to determine what interface a given flow goes out, and it's largely going to depend on what hashing mechanisms are available to the device. The common ones are source and destination MAC addresses and source and destination IP addresses. Higher end platforms can also use things like tcp/udp port to hash on as well.
So let's say the systems are hashing on source and destination IP address and you have a 2 port LAG.
Let's say 10.0.0.1 is trying to reach 192.168.0.1. The device in question hashes this to go out the first LAG port. This means that all traffic between those two IP's would go out the same port. It also means that the flow between those two IP's would be limited to the speed of that port
Now let's say 10.0.0.1 is trying to reach 192.168.1.1, and the device hashes it go out the 2nd port. All traffic between those two IP's would go via that port, and again, throughput would be limited to the speed of that link
So yes, it is possible to utilize both ports and get 2 gigs, just not with a single transfer. A given traffic flow will be hashed to go out a specific interface and the throughput limit for that traffic flow will be limited to the speed of that interface. It's further complicated that how a given device will define a flow varies from platform to platform, so you could run 10+ individual transfers simultaneously between two end points, but if the hashing algorithm only looks at something like source and destination IP, all of those individual transfers would be considered part of the same flow.