Deco , you cant differentiate 2.4 and 5Ghz . Hopefully you are not running anything b/g band ?
I would switch off all devices which are not 5Ghz then check speeds , then switch on other devices one by one
Slowest device in your network is restricting your speeds . The difference is huge between wired and wireless
80/90Mbps seem to be of 2.4Ghz
AX1800 as per specs
5 GHz: 1201 Mbps (802.11ax)
2.4 GHz: 574 Mbps (802.11ax)