Thanks for the replies. I was able to read/write on an ExFAT USB stick actually, but it is only marginally faster than writing to FAT32. I got 3,5 MB/s instead of 2,7 MB/s. It seems strange, because I can write at 20 MB/s using a 2013 model Time Capsule which is five years older than the B1300 and has not received software updates for several years. I figured B1300 would be at least as fast.