MTU correct size

Hello,
I’ve put together a setup in my house for testing, and it’s working, but I think it could be better. It’s basically a dedicated IP that comes from the ISP where I work at. It comes home throught an ONU and then to a RB2011. After this I have a simple router in bridge mode to provide a wireless conection to my devices. I have internet access and everything is working, but I think it’s a bit laggy. MTU on ether2 (DHCP server) is 1480, as it is set on ether1 (gateway).

So it is CCR1036+ (MTU=1500) → VLAN (MTU=1480) → OLT → ONU (Bridge mode) → RB2011 (MTU=1480) → Router (AP mode).

I’ve seen a lot of posts here on how to find the correct MTU but I’m still confused. What would be the right value on it?

Thanks everyone for the attention.

How you understand it’s a bit laggy? Some pings, dumps, traced routes?