From what I can ascertain, a high percentage of those using BearShare 5.1 Beta are semi/totally-firewalled. Out of 11 BearShare 5.1 Beta peers I was connected to, only 3 such peers had more than one Leaf connected to them (or 2 out of 10 since one peer was mine). The other BS I had running had 3 out of 6 with more than one leaf connected to them (again, one being mine). All were the BS 5.1 beta versions. This suggests their BearShare is firewalled. The only reason an ultrapeer would have less than a few Leaves connected would be because they are firewalled in my own experience. (10 hours later & the ratio was 5/13 non-firewalled overall & 2/10 non-firewalled BS 5.1 beta peers.)
This does not seem to apply to other BS versions because they undoubtedly would not be able to become ultrapeers if their BS was firewalled.

BS 5.1 does not have UPnP support or any other port mapping technology. Thus, to run properly as an ultrapeer, BS 5.1 needs to be port forwarded through a router-modem so messages between hosts are not being blocked. I needed to port forward my router for each of my BearShares running on different Windows systems & using different ports. My five BearShares are not firewalled.

If anybody needs any assistance to port forward your BearShare, you can either ask on this forum or else, ask at the portforward.com website. That site has very good guides for the majority of routers available. ie: Router Port Forwarding Guides - PortForward.com (1) you select your brand of router, skip advertisements by choosing close on next window, (3) select your model of router, (4) select the program you wish to port forward for. Then follow the instructions. Sample images are supplied. The BearShare instructions they supply are for the original BearShare 5 version. Edit: Further specific details here: Setting up internal static ip address first

Some people seem to think that port forwarding a router is some complex scientific mathematical formula, but it's really not. Some routers require more steps than others. If you need help you can always ask here or at portforward.com.

Once your BearShare is port forwarded properly, you will find very notable improvements in performance for yourself. Your search results will improve & amplify greatly. It will also greatly help the other BS peers & gnutella community. And others will find it easier to connect to you & vice versa. An ultrapeer blocking incoming/outgoing messages is not good for the network. And some of the newer client versions such as GTK-Gnutella will refuse to connect to firewalled ultrapeers. Being connected for 12 days straight whilst firewalled & without being connected to Leaves does not benefit anybody & blocks lots of messages such as others searches passing through your bearshare at same time. (Have you ever done a search & not got many results? Chances are some of your search results were blocked by firewalled ultrapeers nearby you. This is why firewalled ultrapeers rarely have Leaves connect to them.)

(click attachment to see larger view) . (I squashed everything up a little in the image to try to keep the image small'ish.)

The attachment above shows BearShare 5.1 Beta ultrapeers (Peers) underlined in green to show those that are obviously firewalled. The background is blue because all hosts have been selected. As you can see looking at the Leaves column far right-side of the image, those peers only have between zero to 2 Leaves each. Despite their good minds to stay connected for long periods, their firewalled status steals much of that help away from the network. There are lots of BearShare Leaves that are unable to become ultrapeers & desparately look for BearShare ultrapeers to connect to (that's the way BearShare was designed.)

Of the 3 beta version peers not firewalled, one is mine running from a different Windows system. You will also see I highlighted being connected to 45 Leaves out of a possible 45 leaves (100%) & also highlighted that my BS 5.1 beta is neither TCP or UDP firewalled.
The Beta with only 35 Leaves had only been connected 19 mins & was still establishing themselves. Though lack of bandwidth can possibly be a cause of not filling up all the leaf allocations. I usually connect to 45 leafs within 5-10 mins. And 37 of those are BearShare leafs. The other leafs are usually ShareAza with lots of shared files.

BearShare is an old gnutella technology that still uses GWebCache to connect with. It's even less suiting to the network when 2/3 to 3/4 of the BearShare ultrapeers are firewalled. It's sort of no wonder why a lot of the UDP port packet send out checks fail because so many of the hosts around the BearShare you are using are themselves UDP firewalled & fail to receive the UDP messages/requests, thus giving your BS the UDP firewall message periodically. I can verify this happening after a restart & first peer connected to was firewalled which gave my UDP firewalled status for an hour (but was then ok. BS only checks once/hr.)

We can only help you if you start by trying and helping yourself first. ... It would be nice if we could clean up the BearShare 5.1 Beta pool of peers to be non-firewalled. I doubt anybody will take notice or the slightest care. As I just might lose interest in keeping up the connection updates for people who simply do not care. I've got lots of other things i could be doing.