After updating my system to Ubuntu 16.10 I wasn’t able to synchronize my accounts anymore. The problem was that the banking servers seem to not properly shutdown their TLS connections. Googling around showed this Ticket #259 and Ticket #230. The last ticket gave a hint on what to change in the Gwenhywfar library to get AqBanking back to work. Just to make it clear, it doesn’t seem to be a bug in AqBanking but in the TLS handling of the banking servers.