Yeah, the limited number of slots doesn't help either. I wonder if the current settings are too conservative.
Your seed returns quite a few IPs that don't respond to ICMP pings - not sure what is happening there.
03:01:53 scott:~$ for ip in `dig +short dnsseed.bluematt.me`; do echo -n -e "Testing $ip: "; ping -c 1 $ip|grep 'packet loss'; done
Testing 24.7.158.162: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 50.19.225.254: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 67.242.10.199: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 72.223.56.138: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 76.92.171.255: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 76.123.10.117: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 80.3.173.28: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 80.101.109.52: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 93.186.32.117: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 94.19.17.167: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 97.86.39.50: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 113.255.177.241: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 118.208.226.66: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 173.180.141.86: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 174.119.14.66: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 178.18.129.133: 1 packets transmitted, 1 received, 0% packet loss, time 0ms
Testing 193.86.163.77: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 206.255.99.164: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 216.8.180.85: 1 packets transmitted, 0 received, 100% packet loss, time 0ms
Testing 24.1.117.3: 1 packets transmitted, 0 received, 100% packet loss, time 0ms