Not gonna lie but any kind of SOHO device and have an expectation that you are gonna get 5 years of support is just gonna have you ended up disappointed. (sucks but that is just the nature of the beasts when it comes with SOHO devices)
The whole end of like kernel/support has been discussed a few times over the year or so
https://www.reddit.com/r/GlInet/comments/1gj0q4o/glax1800_running_openwrt_2303_eol_openwrt_version/
https://www.reddit.com/r/GlInet/comments/1pxug8x/soon_to_be_eol_kernel_on_devices/
https://www.reddit.com/r/GlInet/comments/1kgbgos/how_long_are_routers_supported/