eMule can discover sources using eD2K servers and the decentralised Kad network. They provide different ways to find other participants; the actual file data is exchanged directly between peers.
What eD2K servers do
A server helps the client locate sources and perform searches. You connect to an available entry from a server list. If one server is unavailable, another may provide a working discovery route.
The server does not contain every file advertised by the users connected to it. Its role is coordination, not hosting the transferred content. Use a maintained server list rather than old addresses copied from an undated page.
What Kad does
Kad implements a decentralised Kademlia-based discovery network. It needs contact information to bootstrap, after which it can discover sources without a central eD2K server.
The two networks can be enabled together. A working server connection can help introduce known clients for bootstrapping Kad, but Kad is not just another server entry.
Read the connection indicators
The original article explained the two arrows in eMule's network-status icon: each reflects a different network. The client also provides text status in its server and Kad windows.
Colours commonly distinguish disconnected, restricted and reachable states. Read the text alongside the icon, especially if the theme or client version makes a small colour change hard to see.
What Low ID changes
Low ID usually means that the client's selected incoming TCP port cannot be reached. A server may need to help coordinate some connections, and there can be fewer useful source combinations. Kad has its own firewalled status, including UDP reachability.
The original article called the speed impact a myth and then described the limitations. A clearer explanation is that reachability can limit opportunities, while no single ID state determines the rate of every transfer. A well-sourced file can behave differently from a rare one.
Choose the right next check
If neither network connects, inspect basic connectivity and the client log. If eD2K works but Kad does not, use the Kad checklist. If the client reports Low ID, follow the reachability checks. If both networks work but a file waits, look at sources and queues.