OpenWrt and Raspberry Pi4 optimizations

I am using RPI4 as OpenWrt router having static WAN IP on USB ETH adapter (100/100 line) and on eth0 is my LAN.

Doing a lot of livestreaming from remote locations to my VPS (about 15mbit) and that is always working OK. From VPS to our MCR (master control room) traffic goes trough RPI4 running OpenWRT. It works, but I get some lost packets and I would like to optimize network as robust as I can. What would your MTU suggestion be or other tweaks?

From remote locations I am using openMPTCProuter and bonding to VPS. Is there any more robust and safer/better way to chang any of my setups?
Like I described I have a lot of things going one and I need to understand if I have some bottlenecks here? Or I am using/working in the right direction?

What info do I need to provide to get some confidence that in general I have the right tools and equipment for the task. Sometimes I see other streamers spending a lot of their time and money on things that are not efficient. I speak up and help them. Maybe here I am in a position with my setup and it could be that I am not on the right track.