Troubleshooting inability to connect to the Wi-Fi
Networking problems can generally be solved quite rapidly. These are some of the most common problems:
- Ethernet connection is lost when a USB device is plugged in: This is often caused by inadequate power. Use a good power supply and a good power cable.
- Network/USB chip gets too hot to touch: This is normal. In open air at 24 C, the LAN9512 Ethernet/USB chip reaches about 52 C after some time. This is too hot to touch for more than a few seconds, but it is not unusually hot for the chip. The LAN9512 data sheet in Table 4.1 on p.40 says it comes in two versions, rated for operation at an ambient temperature in still air (Ta) of 70 C (commercial) or 85 C (industrial). It uses 763 mW at 3.3V with maximum traffic on 100baseT and both USB ports (Table 4.3.4, p. 42).
- Networking no longer works when changing SD card between two Raspberry Pis: In some distributions, /etc/udev/rules.d/70-persistent-net.rules remembers which MAC address is associated with eth0, so each new device will be assigned as a different interface (eth1, eth2, etc.) due to the different MAC addresses. Editing /etc/udev/rules.d/70-persistent-net.rules to remove the invalid rules and rebooting may help fix the problem. Contact the MedEasy technical staff to execute this fix.