[Hosts]
bUseDefaultServiceProvider = Yes ; always try public.bearshare.net first
bNeverBecomeUltrapeer = No ; never become an ultrapeer
bForwardPublicQueriesToLAN = Yes ; Forward public queries to local LAN via multicast
bNativeCompletionPorts = No ; Use native completion ports for socket I/O
connectTimeout = 10 ; max seconds for connect
handshakeTimeout = 10 ; max seconds for handshake completion
msgTimeout = 10 ; max seconds to receive message
tempTimeout = 5 ; max seconds for temp to send a ping
hostMinorTimeout = 3 ; display time for minor errors
hostMajorTimeout = 10 ; display time for major errors
szAuthUserAgent = "" ; Authorized User Agent
szRejectUserAgent = "" ; Reject User Agent

You have to get an open port on your router to get BS connect.

I think you hit the nail on the head. BearShare versions below 5.2 did not have UPnP support, thus you need to port forward a port for both UDP and TCP in your router.
The ...
bForcedUltrapeer = Yes ; Forced Ultrapeer mode
I think only applies to the 5.1 beta version. I suspect it was put in for testing purposes only.

Those who use BearShare 5.1 or below who do not port forward their router/modem for the incoming ports will be firewalled & damage the network by blocking search messages & also greatly reduce their own experience on the network.