Network issues with 4 gigabit ethernet Qnap

[akagumo]

Hello, I am new to truenas.
I have installed the newest TrueNAS Scale on my Qnap TS-853A on a 128GB SSD connected via USB3.
Setup users, and pools, datasets, Plex.

Transferring data from my computer over gigabit switch I notices avg speeds around 45-70MB/s which seems slow.
Switch shows all connections to NAS at gigabit speed and computers connected at gigabit.
I tried to set MTU on all four ethernet to 9000, and then 8000.
Computers to 9000 jumbo. tried ping tests to NAS.
But then transfer speed was slower at 8MB/s, frustrating.
I set MTU back on ethernet and computers and restarted. but still 8MB/s transfer.
Why is this happening?
How do I fix this?
I also tried link aggregation, but that failed. Read the documentation on Bridge, Link Agg. but Not sure which or why to use them.
Please help.

 

[ChrisRJ]

How large are the files? Depending on their number and size the speed you indicated might be ok. How powerful is the QNAP?

Please provide information about your computer and how you transferred the files. The forum rules explain the level of detail that is helpful.

 

[akagumo]

Files are 6GB to 15GB.
the Qnap nas has a Celeron N3160 1.6GHz quad core cpu.
8GB of ram.
4 - WD Red 6GB the older ones with CMR in RaidZ1
4 x Gigabit RJ-45 Ethernet port
computers are Intel iMacs with 1Gigabit ethernet.

after setting MTU back to 1500 now not even close to 45-70MB/s, instead 8MB/s.
how do I fix that?