Easiest would be to just get the 2.5 Gbps switch (I would try to get a managed switch if that is not too expensive, it opens more options) and directly connect all of the 2.5 Gbps devices via CatX cables (with X >= 5e). Unless your Internet access is significantly faster than 1 Gbps I would not bother yet to upgrade the router (if you are looking for a new router anyway, sure weigh the 2.5 Gbps alternatives).