Im using the Asusor for my needs and placed two 4TB harddisk. inside - non mirrored.

Its great for streaming movies and storing stuff for use, photos, movies, CCTV recording.

Your copying issue has go many variable, one is network speed and such. So it might not solve your issue.

However I recommend a NAS. It helps a lot in storing data.

I started from Dlink DSL-320L and now I just recently upgraded to Asustor AS505T. If you ask me, if its permanent, get 2 bays for NAS system. I used to not to be able to stream content on my phone using my old NAS, the Dlink one. It loads very slow and i would have to wait for so long. I gave up on it shortly after. But with the new Asustor I bought and upgraded, it streams so well as I place all my movies in my NAS and animes. And while I'm eating lunch at my dining room, I can watch my movies and series at ease, provided I am connected to the router network. It does work over 4G as well. I have tested it with 2 phones, samsung and iphone. And i would suggest if you were to get asustor, download VLC so it will be easier to play the movies and easier to edit and fast forward track etc. Im not an expert in this, but I just meddle it to the settings that I want, plus i usually check the hardware and comparing before actually purchasing one. My first Dlink was because I had little choices, and didnt want to spend much on it as Synology at that time was RM800 for a 2bay NAS, so i turned to this Dlink at RM600 then. I also bought a 4TB Red WD for my NAS, and now I have upgraded that to 8TB Red.  The hard disk can be up to you. I have never tried synology or WD Cloud. Although it seemed tempting to, but after i got my asustor, been happy ever since. I also set it to turn off at night about 3am and turn on again at 5pm. Depends on your budget also, the asustor i got was RM1.3k, just the NAS alone mind you, and I had to get another 8TB red disk at RM1k. haha. So yeah, total was RM2.5k around there. Your router should be sufficient enough as Im using the new Asus RT-AX56U router, hence why maybe it streams content faster. xD And it was easy to map to my desktop too. And also tablet (provided in the same network).

Just my opinion and sharing what I experienced.

Using DS918+ keep a lot of media files. Transfer speed normally will get 100mbps if transfering large files. But if u are not intending to store media files for playback (ie 4k video) you can get those entry NAS. Cheaper.

You may consider Synology, ease to use.

Using DS213j

How is it bro? I have not used Synology but I heard it was a good brand. Is it able to stream content to your phone? I know most NAS would support through desktop.

How is it bro? I have not used Synology but I heard it was a good brand. Is it able to stream content to your phone? I know most NAS would support through desktop.

Yes. But usually a 2 Bay NAS is enough to support, all you got to do is upgrade the HDD, thats it. Rm1k+ is also considered quite expensive already bro. Haha. Anyway, as I mentioned, personally I prefer to compare hardware among the same brand. Like Asustor with different models etc. I was considering their cheaper model when I noticed that the cheaper ones are using Marvell Chipset, and only dual core processor and fixed at 512MB Ram or something. xD The one I got is Intel i3 and dual core, and support up to 8GB ram, they gave standard 2GB, but I upgraded to 8GB already. If you're thinking of long term and permanent usage, I'd say you go for a better equipped hardware model. At least you know in the long run it will last a little while longer than older chipsets, the ones which are cheaper that is. I mean, this is all my own opinion when I start to search and compare the models for Asustor. Setting up is also easy, if you have a new drive etc it will pop out automatically when you install it. But there are softwares that need to be installed. Im currently using 2 HDDs, 1 is 8TB and the other is 4TB. I did not raid them, because of different storage capacities. I will upgrade somewhere end of this year if there is a sale etc on lazada or what not. xD Probably get a 16TB drive. Usually for home 2 Bay NAS is more than enough as a single bay can support up to 16TB of storage, if you add both, 32TB is a lot of movies and animes and files combined! As for file i am not sure bro, but seeing as files are smaller in size, i think RM1k+ NAS should be fine with it and would work flawlessly. I think. The gap difference, I am not so sure. But I do just check their hardware so I wont end up buying an older model hardware which wont last me as long as I want it, I estimate to be about 5 years. My Dlink worked well for about that time, I just switched it because my hands itchy. hahaha.

Oh ya, for the transfer rate I'm getting about 30Mbps for large file transfers, usually its all done within 30mins. I usually transfer my newly downloaded movies and series at about that average speed. xD

You're welcome bro.

This is the one I bought;

https://www.asustor.com/en/product?p_id=61

xD

If you want more hardware power, get an Asustor.. AS5304t or AS5202T..
both are equipped with newer celeron processor which is better for video transcoding (plex media server) and newer 2.5GbE network card..
Previously was my target but Lazada 12.12 had a good offer for DS918+ that hard to resist..

Don't need overpriced "branded" NAS for me.

Pentium dual core
Gigabyte Z170X Ultra Gaming
Crucial 8GB DDR4-2666
FSP Hexa 500W
Corsar Carbide 400R (Can install 10 HDDs total)
Cooler Master 4-in-3 device module
WD Red Pro 3TB
WD Gold 3TB and 4TB
Seagate Skyhawk 8TB X3

Obviously. What can you expect for casing that allows you to install 10 HDDs. lol

You don't store important photo in SSD, or any single storage, you store important stuff in multiple HDD, external HDD, cloud, NAS,
just in case one down, you still have other as backup.

SSD aren't immune file system corruption, lightning strike, human error (accidental format or deletion, lol) ect.

I think there's something that limiting your transfer speed, maybe the flash drive, or FTP or you choose USB 2.0 mode on the router for compatibility.
Using 2.5 HDD I can easily get 60MBps transfer if using LAN or 20MBps if using 5ghz
Even if using NAS this will be the same speed that I'm getting. Well, 5ghz speed can double if I install the software on my PC to get 800mbps connection but I'm contend with 20MBps.
To have decent NAS with 4 bays will cost almost 2k
depends on size, 2 HDD might cost 1k to 2k
PC as NAS maybe can save 1k but need to do everything DIY
It's not a cheap thing no matter PC or dedicated NAS.

One thing for sure is at least have RAID-1 on the system if go for PC or dedicated NAS. Having such system means you will have Terabytes of data, although the data might be unimportant or can be downloaded again it will be a hassle and time consuming if one of the HDD spoil. If you not gonna store Terabytes of data then you don't need to get PC or dedicated NAS

My experience flash drive even if USB 3.0 the speed is not great. This is even flash drive directly connected to my PC.

No, on LAN easily can hit 60MBps. To hit 100MBps depends on situation, whether router got download anything, network traffic by other devices, even Windows or router issue also makes it cannot transfer at max speed. Sometimes after restart everything then can hit max speed. Router transfer to PC is easier to hit max speed while PC to router is slower.
I forgot to mention I'm using SAMBA for transfer, you using FTP so that might also give different result.
Also check if enable USB 2.0 mode on the router. That will cause the transfer to be slower.