The P2P / Battleservers are not the issue. It is the games engine, for whatever reason the way the engine handles a matches data means that a player cannot rejoin at a certain point of a match. This is also why you cannot rewind when watching replays.
No they are not the issue. Some people mistake battle servers for actual dedicated servers, I was just pointing out that battle servers are simply relays.
so we dont have any solution for this problem, right ?
Not unless Relic wants to overhaul the engine's network structure which would be very costly. So basically no. The only solution is to get a stable network connection.