If that's the setup, the only way anything would run more than 1Gb is if the Synology is doing SMB-multichannel (which if they setup 4x1Gb LAG, then it's not SMB-MC).
[edit] reading the article, they do have the Syno setup for SMB-MC and that's the only reason this wasn't stuck at ~120MB/s
alt Hacker News
If that's the setup, the only way anything would run more than 1Gb is if the Synology is doing SMB-multichannel (which if they setup 4x1Gb LAG, then it's not SMB-MC). [edit] reading the article, they do have the Syno setup for SMB-MC and that's the only reason this wasn't stuck at ~120MB/s