Speed matters less than you probably think
Modern online games typically consume 3-10Mbps while you are actively playing. Even a 30Mbps connection is technically sufficient bandwidth for the game itself. Where download speed becomes relevant is in downloading games, which can be enormous, and game patches. For that, faster is more convenient, not a performance issue.
Latency (ping) is what actually determines your gaming experience
Ping is the round-trip time for a data packet to travel from your device to the game server and back. Under 20ms is excellent. 20-50ms is very good and all online gaming is comfortable. 50-100ms is acceptable for casual gaming but starting to feel slow in competitive titles. 100ms or more causes noticeable lag.
Jitter and packet loss: the hidden culprits
Jitter is variation in your ping, when latency bounces around rather than being consistent. A connection averaging 40ms but varying between 20ms and 80ms will feel worse than one holding a steady 50ms. Packet loss, where chunks of data are dropped and have to be resent, causes the sudden stuttering you sometimes see in online games.
What connection type is best for gaming?
Full fibre is the gold standard: consistently low latency, minimal jitter, and no copper degradation. Ethernet cable to the router beats WiFi for gaming, full stop. It eliminates the latency variation that wireless introduces.