While Phex accepts connections from all clients without restrictions, Limewire generally preferes other Limewires over other clients. In some versions more in others less..

Bearshare even only accepts UP2UP connections from other clients.

When acting as a UP you usually should have no problems finding other UP. Maybe a small warmup time is necessary, when Phex wasn't running for a longer time.
Phex actively searchs for UP and advertises itself to accept Leafs.
Finding Leafs (or better Leafs finding you) is a bit more difficult because of the vendor preferencing reason. Leafs from Limewire always have the tendency to prefere other Limewires and might only accept other hosts if they have problems finding Limewires. Bearshare Leafs will never accept any other client.

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