A browsing tab can get stuck at “sent a push request...” with no explicit failure notification / browsing through ED2K always fails

[abolibibelot1980]

Quite often when attempting to browse a user's list of shared files, the new tab gets stuck at “sent a push request, waiting for connection...” and can stay that way for hours, yet if the client is indeed unreachable, an explicit failure notification appears soon after the request in the Network / System area, saying for instance :
“[19:17:27] Unable to initiate a connection to xx.xxx.xxx.xxx to browse user.”
(In other cases it displays quite quickly : “Unable to connect to host to browse user” — I'm not sure what is the technical difference between those two situations.)

Also, loading a list of shared files through the ED2K network / protocol always fails, even though the same client can be browsed through “G2” or “HTTP” (or can be browsed with eMule which as far as I know only connects through the ED2K network / protocol). Usually when attempting to browse through ED2K it gets stuck at “Downloading browse response (0%)”. Sometimes when doing a search, a source can first appear as a Shareaza client (usually browse-able), then spontaneously turn into an eDonkey2000 client (almost always non-browse-able).