Like I said I was trying to feature out what the problem is. I have a DD-WRT router that uses aiccu to connect to sixxs broker and uses radvd to broadcast IPv6 connection to devices connected to the said router. I used a startup script that execute aiccu ONEC every restart. The first time I tried to set thing up a couple of months ago I had to do some tinkering and as you can imagine I was blocked due to frequent queries that was caused by restarting/resetting the router. Back then I just had to get all the configuration finally right and waited for about half an hour and execute aiccu, by which time I was already unblocked. Everything went fine from that point on and I had a steady connection for about 2~3 months in which time I only restarted about 2 times due to router firmware upgrade. Two days ago I had to reset my router again because I needed to setup a guest wifi network and messed up to the point that even wired connection the the router LAN cannot access the router. After reset I loaded the old working configuration but aiccu was not working. I was puzzled and restarted about two times and then realized that my router clock was not NTP synced so all aiccu attempt was rejected. I fixed that problem but then I got "500 Hard Block". I thought it was just like last time and waited for an hour and tried to connect to sixxs and failed again. So I went to sleep WITHOUT putting any aiccu comment in a looped script. The next morning I was still getting "500 Hard Block" so I realized this block was different from last time. I left for work, again without putting any aiccu in any loop. When I came back home I tried to connect and failed one more time. So I decided to figure out if it was my sixxs account or my IP that was blocked, and if my startup script was not configured right somehow (which is unlikely because it was exactly the same script that was severing me right for months). I used another WAN IP (a 4G hotspot shared from a laptop to the router's WAN port by ethernet connection) and this time I was able to connect to sixxs broker without any problem. This tells me that it was indeed the IP address that was blocked, and the router configuration/my sixxs account should be functioning correctly. In the entire process I NEVER put aiccu in any looped script that automatically reconnects. And my overall trial to connect (through startup script or manually running aiccu) was definitely fewer than ~20 times. If you are seeing hundreds of queries I cannot understand how it could possibly come from my configuration. I now have commented out the aiccu line in my script and disabled IPv6 in my router settings. I have radvd set up that uses the subnet associated with my tunnel, could it be the culprit that constantly queries the server without explicitly running aiccu? This radvd was also untouched and worked fine for months. In any case I now have radvd disabled as well and there is nothing on my router that should make any connection to sixxs server now. Thank you for bearing with me with my lengthy description so far. As you can see I now am trying my best to avoid any connection attempts to sixxs. But also you said that the block is not associated with my account, so I think it is possible that someone who shares WAN IP with me (everyone in the apartment building are behind NAT and uses a single IP) who abused the server and caused the block. This could have happened a long time ago and still is happening due to some faulty configuration. Since I had a continuous connection to sixxs for weeks prior to my recent router reset, I could not have known about this until a reconnect attempt was made by me (I'm assuming that if one establishes and maintains a connection to sixxs broker, one would not be kicked out of his current connection due to his IP being blocked until the aforementioned connection is dropped and a reconnection attempting is made.) I was not I'm not tying to find an excuse for myself but I really need to figure out whether is was caused by me and if so of course I'll dig more and find out what was wrong. If you can have a look at your record now and tell me when did the hundreds of queries start and if it is still ongoing I could at least have an idea if I was looking at the right direction. Thanks in advance.