Well, yes, you might have guessed, I hav ebeen working with Cisco Networking gear since the mid 90s. In fact we just shutdown our last Cisco router that had a Ehternet interface on it two weeks ago at work. We still have several that have FastEthernet interfaces.
Our main guy working on phone systems just received his 30 year service award, and when were we discussing some of the old systems we used to have over the awards lunch he joked about that fact that our company policy should be that if the light comes on we still use the equipement. Since it seems we don't upgrade until something breaks.
I do still struggle with a few of the older IT guys at work about not locking the 1G interfaces on the Cisco switches and letting them auto-negociate. Most of the Cisco gear we have that is only 100M, has been in service since the 90s, and likely still suffers from the issues, I have never had issues when having them locked as long as you make sure both sides are locked to same settings.
I also noticed when looking at your reply, taht the earlier paste of the network settings appear to have been a copy from earlier testing, and werent the final results, they should have been as follows. The earlier post shows 1G/Half without flow control.
re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
inet6 fe80::20d:b9ff:fe3a:4ed8%re0 prefixlen 64 scopeid 0x1
inet 192.168.5.1 netmask 0xffffff00 broadcast 192.168.5.255
media: Ethernet autoselect <flowcontrol> (1000baseT <full-duplex,flowcontrol,rxpause,txpause>)
This of course is my home Firewall, which I do run OpenVPN on to connect to the office.