add eui64 address generation instructions to arch readme

infrastructure/graduated/arch/README.md

@@ -46,6 +46,8 @@ instructions for building a:
     - [AppImage](#appimage)
     - [Overriding .desktop files](#overriding-desktop-files)
       - [Flatpak](#flatpak-1)
+  - [Networking](#networking)
+    - [IPv6](#ipv6)
 
 ## Installation
 
@@ -840,4 +842,16 @@ find /btr_pools/root/root/ -name '*.desktop' 2>/dev/null
 
 ```bash
 cp /var/lib/flatpak/exports/share/applications/... ~/.local/share/applications/
+```
+
+## Networking
+
+### IPv6
+
+Set address generation type to eui64 with nmcli:
+
+```bash
+nmcli connection modify Wired\ connection\ 1 ipv6.ip6-privacy 0
+nmcli connection modify Wired\ connection\ 1 ipv6.addr-gen-mode eui64
+systemctl restart NetworkManager
 ```