Veja as duas principais respostas para a pergunta "Programa do Windows para limitar largura de banda de outros programas? ". .
Primeira resposta
I use NetBalancer. While its a paid software, a free version exists, but can restrict traffic on upto 5 processes at a time.
Segunda resposta
I use Net Limiter, which is free.
NetLimiter is an ultimate internet traffic control and monitoring tool designed for Windows. You can use NetLimiter to set download/upload transfer rate limits for applications or even single connection and monitor their internet traffic.
Along with this unique feature, Netlimiter offers comprehensive set of internet statistical tools. It includes real-time traffic measurement and long-term per-application internet traffic statistics
No mínimo, parece que o NetLimiter permitirá que você limite a quantidade de dados por adaptador de rede, embora eu não possa garantir pessoalmente que ele suporta uma mudança automática para outro adaptador.