So you deleted your LW preferences folder, replaced the Gnut. file?
Usually 'one' or a combination of those suggestions in that link will work. The new version LW generally needs its older prefs folder removed, newer Gnutella file & sometimes if only temporarily, the advanced options disabled.

The prefs folder being deleted will mean you will need to reset all options again, so make a note of them before hand, or repeat the process of setting changes. Close LW between each change.

In LW's Advanced -> Firewall, Change listening port to one between 49152 - 65535.

BTW if incomplete files are large amount, this can also affect connection by interfering with LW's communication with the modem/router & UPnP failing as a result.