Abstract: Topological twists of 3d N=4 gauge theories admit boundary conditions that support vertex operator algebras, initially constructed by Costello and Gaiotto. I will review this construction, then discuss current work (with A. Ballin, T. Creutzig, and W. Niu) proving equivalences of these vertex algebras under abelian 3d mirror symmetry, and relating their module categories (a.k.a. bulk Wilson lines and vortex lines) to representations of certain quantum supergroups. We also directly relate these categories to those that have appeared in recent work of Oblomkov-Rozansky, Hilburn-Raskin, and Gammage-Hilburn on line operators.