If that is the case, i don't understand the recent drop in race room quality on weekends many here are experiencing for about two months. Considering no changes were done in the GT6 network code (no GT6 update, only PS3 FW update in this timespan) the only explanation would be a global decline of internet reliability during certain times on weekends -- likely for some local spots but unlikely globally. And a poorly set-up console doesn't work better during weekdays. Or maybe GT6 is using network code from PS3 firmware, and the recent firmware update made peer-to-peer networing more sensitive to a fragile network?
I was quite happy with the GT6 online experience, but for two months now i can be sure to have problems during weekend evenings (UTC+1 timezone here). And it's not about just me dropping out of rooms full of people happily racing -- during these times everybody has problems entering and staying in a room. If you have 1-2 days a year with network problems you would say bad luck, but if you have 8 weekends out of 8 weekends with network problems, no problems on other days and 1 year with no problems before it's hard to call it coincidental.