FTTP gigabit lan half speed and 100% cpu

[WKS]

Having latest available updates and trying fixes and tuning on internet hours without success avantech ppc-3100 ppa industrial computer, this one has realtek not Intel duel gigabit lan and is running pppoe full duplex 1000

I have tried the various tuning and config suggestions without success 1.86 MHz Intel 64 bit, 4gb ram and 32 Gigabyte SSD.

Previously on 70/20 fttc it was flawless.
900/100 it chokes at half speed compared to isp router.
If I could I would swap out realtek lan, but soldered in.
I did find driver suggestions 2 years ago mentioned, but they won't load due to openssl version.

It's frustrating a lesser isp router full speed and pfsense chokes 3-500m/bit on same connection.

I'm beginning to think new hardware, this is 25w fanless, so disappointing to abandon.

Thank you