SOLVED****** Despite ISP assurances, it was an issue with the ISP MODEM which has been repalced and the issue is resolved.
Having a bit of an issue with speed using PPPOE to connect to the internet.
I have a NanoPi R2S running OpenWRT.
I have a 1 gbps internet connection.
I have my internet service set to allow PPPOE connection.
If I use my computer directly connected to the ISP's MODEM I can get 1000 mbps speed reliably and consistently.
If I connect my NanoPi R2S to the MODEM I can only achieve 100 mbps speeds when using PPPOE to connect to the internet.
The R2S hardware supports 1000 mbps, and achieves 1000 mbps internet if I use DHCP for the internet connection but as soon as I switch to PPPOE for the internet connection it gets only 100 mbps internet.
I have eliminated bad cables as the cause by testing thoroughly and replacing every part of the setup with known good hardware.
Any help in figuring this one out is hugely appreciated.