A number of people are currently working on support for multiple Realtek based switches, including some 2.5G models.
https://forum.openwrt.org/t/support-for-rtl838x-based-manage...
https://gitlab.com/bkoblitz/openwrt-rtl838x
Note that biot.com link above is now dead, but they previously had a nice big table of devices and info. Might want to check wayback machine for that.