Linksys currently has a router series that by report, are all the same internally. On the low end, the E2500 is limited to N600. The same report says it has AC1200 hardware capability.
https://wikidevi.wi-cat.ru/Linksys_E2500_v4
I can imagine that Linksys must have some mechanism to prevent someone from buying the cheapest hardware variant and flashing it with firmware from a more expensive version.
In this E2500 v4 thread, the firmware installation had to work around a signed image.
https://forum.openwrt.org/t/support-for-linksys-e2500-v4/56695/12
Anyone aware of a work-around for Linksys image signing?