How to optimise P2P connectivity/connectability?

Does anybody know of any particular tweaks to firewall/sysctl.conf (netfilter) that can be made in order to support a client with a torrent client (qBittorrent) with over two thousand actively seeding torrents? Download throughput isn't what I'm after, to be clear. I'm looking to optimise my connectivity and/or connectability to peers such that I connect to the greatest number of peers and upload to them at the highest possible rate as is possible within the confines of my connection.

One thing I've found thus far is the SYN-Flood protection measure in the firewall, as in this post. Moreover, one thing to be noted is that the router itself is already running a VPN (Mullvad) bound to all interfaces and serving to clients - port-forwarding already enabled though.

Additionally, just as an aside: DNS resolving/caching seems, in my experience, to hold a good deal of influence over torrent performance as well (although the specificities elude me). Rakshasa points towards this importance in their rTorrent Performance Tuning. I'm currently using Unbound and it seems utterly obstinate in its non-compliance to perform well for torrenting thus far - comparatively to when I ran Pi-Hole and Unbound on a VM wherein the torrent client was on the host computer.