I have noticed a lot of errors on WAN and LAN (IN).

pfSense has been up for: Uptime 6 Days 00 Hour 13 Minutes 09 Seconds

PU Type Intel(R) Xeon(R) CPU E31225 @ 3.10GHz
Current: 3100 MHz, Max: 3101 MHz
4 CPUs: 1 package(s) x 4 core(s)
8GB RAM
1x120GB SSD

What should i do to see what is causing errors?

All cabling is brand new, replaced about a month ago.
(I understand that it could be a bad cable as well, even though its 'new').

Any suggestion where / what to look for?

Tnx