Hi all. I am a bit new to mikrotik. How can i make sure that my LAN is unaffected even when my the internet bandwidth is fully utilized. I connected two AP to the router. My clients connect through the AP. I set up hotspot to manage bandwidth allocation but when ever my internet bandwidth is fully utilized, the whole network becomes slow and sometimes unresponsive. I need a solution please

simple solution would be add a gigabit switch between the AP, then connect the switch to the router.

now, since this is a Mikrotik forum,
what hardware and firmware version are you on?
have you monitored the router CPU when internet is fully utilised? if it's high then router is too busy and consider an upgrade.
things might help
check all your LAN port is on the same bridge and hardware offload enabled on the bridge.
depending on that routerboard you are using, make sure the two APs are connected to the same switch chip so that traffic between them should be wire speed.

Hi

Do I mean to give priority to lan traffic to/from internet over the hotspot traffic?

If so what is needed is queueing, https://wiki.mikrotik.com/wiki/Manual:Queue. There are two options "Simple Queue" & Queue tree.First is incompatible with FastTrack (a method for optimisation of traffic processing).

Post your current config to clarify your current situation (/export hide-sensitive compact).