Create software/support chapter for common support requests

Signed-off-by: Egor Savkin <es@m-labs.hk>

src/SUMMARY.md

@@ -16,3 +16,5 @@
   - [Sinara 8452 DSP Stabilizer](./hw/stabilizer.md)
   - [Sinara 9805 RF Power Amplifier Booster](./hw/booster.md)
   - [Sinara 8451 Thermostat](./hw/thermostat.md)
+- [Software/Support](./sw_sup/software_support.md)
+  - [Networking](./sw_sup/networking.md)

src/sw_sup/networking.md

@@ -0,0 +1,23 @@
+# Networking
+
+This page should help solving common network/related problems,
+a-la `I can't connect, please help`.
+
+## Common problems
+
+1. `device_db.py` has misleading `core_addr` address.
+2. PC and the crate are in different subnets. They should be in the same network. Also you may want to directly attach the Kasli to the PC.
+3. Network restrictions/problems on your router, either by IP, MAC, protocols or anything else.
+4. Wrong configuration of the Kasli. Change IP or MAC address to correspond your network. For ARTIQ-8, add 
+   network mask to the `ip` setting on Kasli, like `192.168.1.75/24`.
+5. Incompatible Ethernet cables/SFP RJ45. Try different cables and SFP adapters. 
+   We usually test them with CAT6 cables, but lower categories should be supported too.
+6. SFP or Ethernet are not pushed til the end.
+
+## Ways to diagnose
+
+1. `ping` the device. If destination is unreachable, than it is either didn't connect to the network
+    or connected to different address. If the packets just do not respond then it is not as clear, we cannot know all the truth.
+2. UART logs. TODO here is a link to ways to obtain them
+3. `nmap` and `arp` to scan your network to help your Kasli get discovered. May be restricted in your network.
+4. Become a router and capture all the packets when your Kasli tries to connect to the network.

src/sw_sup/software_support.md

@@ -0,0 +1,8 @@
+# Software/Support
+
+In this section you'll find instructions, tips and hints mostly
+regarding software. The main intend of this section is to ease the support
+process, which often includes answering similar questions and solving similar problems.
+In the future, it may be revised and added to the official ARTIQ manual.
+
+I hope that helps!