I don't know what they're doing, but Mikrotik can perhaps route that → https://mikrotik.com/product/ccr2216_1g_12xs_2xq#fndtn-testr... and is about the cost of their used thing.
And I think this would be a banger for IPv6 if they really "need" public IPs.
Exactly what I came in to say, CCR2216 can do this for < $2k, and does it well.