5K subscribers on a single port/handover VLAN for any modern BNG should
not be a problem...
Assuming you're sticking with IPoE/DHCP and you really want to split
subscribers over multiple BNGs, I'd do something like this:
1. Present the backhaul VLAN to your N BNGs. You will need to use
Intel NICs are very twitchy indeed about non-Intel optics. If you're using
non-Intel optics you typically need to tell the driver to enable unsupported
optic mode.
Since you say some packets are disappearing rather than the link not coming up
at all, it's probably not this, but I'd strongly
