[arch-general] manually configure network

[mick howe]

I've just changed ISP and I can't get the changed configuration to stick.

I'm using 'static IP address - manual assignment' from Network
configuration wiki page.

I need to change my address from 192.168.1.0/24 to 192.168.20.1/24.

using iproute2 tools as per wiki I can get everything working UNTIL I
reboot, at which time some of the settings show the old values and others
the new.

I've been manually configuring these settings without problems since I
started using linux in 1994.