This is a continuation of the discussion that developed in another topic. I thought that it would be best to create a new topic, so that the information might be easier to find by other people that might be interested in this.
Setup: Windows 7 x64; rclone v1.51.0 (os/arch: windows/amd6; go version: go1.13.7); Samsung 850 EVO and Patriot Burst SSD drives (used in the tests); Marvell Yukon 88E8001/8003/8010 PCI Gigabit Ethernet Controller; ISP plan: 500 Mbps download, 100 Mbps upload (speedtest.pro confirms those numbers; ping = 12ms); I have already created an individual client ID for rclone and I can connect to gdrive without problems;
Issue: I can only get about 20% of my upload speed (i.e., 2.3-2.5MB/s) when uploading or downloading a single file via rclone (see Stats 1). This also happens with FileZilla Pro, Mountain Duck or Air Explorer, although with Air Explorer I can get up to 4.7MB/s per single file. I can successfully max out my upload (about 12MB/s) when uploading or downloading multiple files (see Stats 2). I can also max out my upload (about 11-12MB/s) when uploading a single or multiple files via Chrome or Opera.
Stats 1
C:\Users\an531\Desktop\Rclone\rclone-v1.51.0-windows-amd64>rclone copy "B:\file" gdrive:\ -P --drive-chunk-size 128M
Transferred: 118.684M / 2.261 GBytes, 5%, 2.498 MBytes/s, ETA 14m39s
Transferred: 0 / 1, 0%
Elapsed time: 47.5s
Transferring:
* file.7z: 5% /2.261G, 2.517M/s, 14m32s
Stats 2
C:\Users\an531\Desktop\Rclone\rclone-v1.51.0-windows-amd64>rclone copy "C:\Users\an531\Desktop\test3" gdrive:\ -P --drive-chunk-size 128M --transfers 5
Transferred: 176.199M / 396.643 MBytes, 44%, 12.022 MBytes/s, ETA 18s
Transferred: 0 / 5, 0%
Elapsed time: 14.6s
Transferring:
* test1.rar: 42% /79.329M, 2.323M/s, 19s
* test2.rar: 45% /79.329M, 2.462M/s, 17s
* test3.rar: 45% /79.329M, 2.455M/s, 17s
* test4.rar: 44% /79.329M, 2.386M/s, 18s
* test5.rar: 44% /79.329M, 2.453M/s, 18s
@thestigma suggested to contact the ISP once we know how to get the IP for the gdrive server to which I am connecting to via rclone. However, I honestly doubt that they will be of any help. Most likely, I will get reconnected 5-10 times to different people just to finally hear that they'll call me back, which will never happen. I'm still waiting for some of those calls since the 20th century...
Therefore, I would really appreciate any information that might help me solve this issue. It might have something to do with router or port settings.
Thank you for your time and help in advance.