`netstack.InboundUDP` jeopardizes all future `gonet.UDPConn`s

[ignoramous]

netstack(tun).InboundUDP() (used by udpmux.go to vend netstack routes for remote IPs a mxconn isn't connected to) seemingly results in ALL subsequent UDP connections to timeout / non responsive.

firestack/intra/netstack/udp.go

Lines 85 to 97 in 23f8b88

	func InboundUDP(who string, s *stack.Stack, in net.Conn, to, from netip.AddrPort, h GUDPConnHandler) error {
	newgc := makeGUDPConn(who, s, nil /*not a forwarder req*/, to, from)
	if !settings.SingleThreaded.Load() {
	if err := newgc.Establish(); err != nil {
	log.E("ns: udp: %s: inbound: dial: %v; src(%v) dst(%v)",
	who, err, to, from)
	go h.Error(newgc, to, from, err)
	return err
	}
	}
	go h.ReverseProxy(newgc, in, to, from)
	return nil
	}

We see similar "hang ups" in a reverse scenario with WireGuard, which tries to invoke netstack(wg).Outbound...() => netstack(tun).Inbound... when it sees new destinations (inbound).