File transfer speeds over LAN network (wired) - very slow, random

ok folks.......i am begging someone on here to help me - on the verge of going back to windows 7. Tried everything.
help me. please.

i have an x99 chipset pc, i7 5820k, 16gb ram, gtx nvidia 970 - its a good pc (meant to be anyway............).
it's connected directly to my router, as are a few other pc's in the house including a laptop - all via lan cable, as is my NAS drive.

a few weeks ago i noticed file transfer speeds had dropped, really slow. I've tried all sorts, including 2 fresh formats trying a combination of things. Different slots on the router, different cables, the whole 'large send offload' disabled thing, everything.
None of it works.
I've been doing side by side tests, vs my Asus laptop (also on windows 10, and the last thing i'd expect in the house to work properly) - transferring the same file, from the same location on my NAS, to a local drive (ssd drives both on laptop and on pc).
With the laptop i get average transfer speeds of this 9gb file of 50-70 mb/s, every time, consistently, No problem at all.
With the PC, one time it will start at 55-60 and slow right down. Other times it'll start at 30 and again slow down.
Or it'll stay at 30.
More often than not, it starts at 30-40 then will slow to 15-20.
On the laptop its a consistent 55-65 and stays there for the entire file.

What the hell is wrong with my pc?
I've done the exact same tests on my little shuttle pc in the lounge, a crappy thing with a simple i3 cpu, no graphics card. No issues at all - i can scroll through files on the NAS located upstairs smoothly with no issue, using video editing software for instance.
So this is definitely a PC only issue, it's not network or router related - as the downstairs pc + laptop check out fine.

Here's a full list of things i've tried to fix it:

- tried different lan cables
- tried different slot on router
- clean format, update windows, then install mobo drivers
- clean format, install mobo drivers, then update windows
- updated all mobo drivers including LAN driver
- removed gigabyte lan driver and tried using default windows one installed on restart.
- gone into the properties of the adapter - disabled that 'offload' thing as mentioned above

none of it has made any difference. This is after 2 x clean format attempts, no other programs installed.
Why has it started doing this????

It's as if its detecting a high speed of transfer from NAS to PC and the pc is throttling it down or something.
Is there any program that will let me see what is causing the speed drop? anything else i've not tried?

pleasee help! i really don't want to have to install windows 7........ need dx12 for gaming in future.

Checked Netbios is enabled , not on Default ? (on all PC's on Win 10 , it seems to be an issue for some)

Also if Jumbo Frame is Enabled and your Router or the other PC can't use it , it will cause issues like this . EVERY DEVICE on the LAN MUST Support JumboFrame if you use it. ie my C7 ARCHER can't.... everything else can....



If that doesn't help , this is my goto list I posted in another Thread for them to check too.

Ethernet network between 3 Windows 10 PCs problem - Page 3 - Windows 10 Forums

Kbird said:

Checked Netbios is enabled , not on Default ? (on all PC's on Win 10 , it seems to be an issue for some)

Also if Jumbo Frame is Enabled and your Router or the other PC can't use it , it will cause issues like this . EVERY DEVICE on the LAN MUST Support JumboFrame if you use it. ie my C7 ARCHER can't.... everything else can....



If that doesn't help , this is my goto list I posted in another Thread for them to check too.

Ethernet network between 3 Windows 10 PCs problem - Page 3 - Windows 10 Forums

thank you, i will try and report back - my router is also C7 archer.

The stalling in performance sounds like JumboFrame (cos of C7) or Large Offload Send which I forgot last night, I have now disabled both on all my NICs too.

I recently started experiencing this issue on 2 PCs. File copy between PCs and a file server became excruciatingly slow, about 10Mbps over my 1Gbps connection.

The PCs had recently been moved from one room, where they were connected through a series of 3 switches (one at the PC site, my main backbone switch, and a switch at the server site), to another room where they were only connected through 2 switches. (Direct thru wall jack to main backbone switch, and the switch at the server site).

While trying to troubleshoot the issue though the usual means (disabling LSO offload, etc.), I noticed something peculiar - my switches seemed to be acting as dumb hubs, re-broadcasting everything everywhere.

I power-cycled all network infrastructure (switches and router), and the problem disappeared.

Hopefully this helps someone else like me who has gone through all of the other steps out there to resolve this and still received no joy.