LAN's connect computers together in a small physical environment. The most popular LAN network today is Ethernet. There has been many forms of Ethernet cabling (AUI, 10base-T etc) and different speeds 10Mb, 100Mb, 1Gb and 10Gb/s).
WAN's are used to connect networks together over long distances. The most reliable long distance connection in South Africa is DIGINET, but is very expensive. Less expensive ways of communicating is with ADSL, 3G or satellite. Satellite communication is just good for internet access.
Communicating over the internet is full of peril. We need to protect ourselves against it. Depending on the complexity of the requirements we may decide to use VPN (Virtual Private Network). Most of the time we use Open VPN.
Wireless networks are used mainly in two situations. The first is for a few computers is a small network, closely spaced. The closer the computers are together, the better the communication. In my experience I avoid these kinds of networks. However I use a network like this in my house. The access point is strategically placed in the centre of the house. The signal travels through two single brick walls and we get adequate communication. The second is for communcation over longer distances with antennas. Here we had great success. When you have line of sight and the right antennas, you can get many kilometers.
What is nice about 3G is that is can be used at almost any location in South Africa. Where there is cell phone connection, there is normally 3G available. The one drawback about 3G is latency. (This is the amount of time it takes a signal to travel to the destination and back.) This is drawback when using interactive programs. To increase speed, we often use a terminal server (TS) to run programs on. With some programmes (like SYSPRO) it was found that that it is better not to use the terminal server if the 3G latency is high. However, this latency problem is being reduced all the time.
DIGINET is the most reliable form on communication in South Africa. This is more a political issue than anything else. When remote sites can not afford to be down, we use DIGINET. Even then we sometimes use ADSL and 3G as a backup to DIGINET. In one instance a client was down for more than a week on all of their DIGINET lines. Linking remote sites with DIGINET requires a router at both ends of the link. Normally we use Cisco routers.