I am still searching alternative software or Web server with snmp protocol. Flint 2 does have space storage and ram, possible install mini Web server for example Cacti?
Any suggestions? What I have?
Raspberry pi 4 installed only Homeassistant os
Qnap NAS
Flint 2
I saw goodcloud has statistics traffic but I wish that make in local router.
Thanks
What. 
You need some simple bandwidth tool - which is already included in the OS itself, as you can see in luci graphs. Refer to this to find some other tools: [OpenWrt Wiki] Network monitoring
SNMP is only needed if you want to get information from other devices. In that case you should go with Zabbix, Icinga, Nagios or any other network monitoring solution.
I tried how to install zabbix server and give up, I need another small PC for server. Qnap nas was hard instruction with emulator things.
What I know flint 2 have web server (ngix) but I don’t know how to add things and mysql databases…
My goal I want to see how much traffic each devices
Hmm since you talk about snmp i guess you want to look into this topic here in openwrt forums.
Theres idd also nlbwmon but i don’t know if that connects with snmp 
, but theres alot of suggestions made there.
In that case: Don’t do it.
Don’t use the router for it. Go for a vServer/VM first and try to play around.
And this ^, constant writing will decrease the lifetime of your router.
I see alot of people use a exporter like prometheus which is idd on a other server.
In my case i use nlbwmon and write to a usb stick😄