Yes, but isn’t the 40Mbps a bottleneck? If I have 3 devices with Netflix all at 4k (which supposedly uses 25Mbps) while gaming, won’t the latency be affected due to the traffic on the line?.

Why do you need to connect over your Landlord’s router, for privacy I would recommend using a VPN but I digress.

Anyway, you can just measure your speed/latency to any near server. I would just Ookla’s speed test or any game that has that functionality.

40Mbps is not really much so unless the other devices are using the internet connection constantly you are at no risk. You could also limit other devices speed or set QoS so your PC or console has priority.

This is based on my empirical knowledge, so if anyone can correct me please do so.