I've noticed something curious in my C7 v2. I have one device connected 24h/365d to my wifi (mobile phone).
Mon Jul 23 23:13:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Mon Jul 23 23:23:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Mon Jul 23 23:33:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Mon Jul 23 23:43:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Mon Jul 23 23:53:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:03:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:13:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:23:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:33:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:43:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 00:53:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:03:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:13:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:23:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:33:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:43:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 01:53:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:03:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:13:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:23:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:33:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:43:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 02:53:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 03:03:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 03:13:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 03:23:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
Tue Jul 24 03:33:39 2018 daemon.info hostapd: wlan0: STA XX:XX:XX:XX:f8:44 WPA: group key handshake completed (RSN)
And every 10 minutes is "handshaking".
In previous firmware versions I never saw something like that. It's not a problem because everything works fine.
The same is happening with other wifi devices, every 10 minutes handshake.
That "group key handshake" is part of the WPA protocol, and is a security feature, those messages are completely normal. You can change the interval, and 10 minutes is the default value. You probably did not notice those messages before, of your previous firmware was silent about that feature, or perhaps it was disabled for some reason.
Changing the rekeying intervalls to long intervalls (10 minutes are chosen for a reason, if you make it 5, 15 or 20 minutes would be fine), orders of magnitude beyond its defaults, you do make cracking the encryption significantly easier.
I think that tmomas was trying to indicate that it makes no sense to mass-update all links for 17.01.5 for just a few days before 18.06.0 gets released.
I think it does as there will be devices which will not be supported by 18.06 anymore. Otherwise, if updating the micro versions is deemed too much effort then we should drop them as they provide little value. A mere 17.01.x or 17.01 might be more useful then.
But surely it must have been a lot more work making 17.01.5 than updating the links for it? I think most people will assume 17.01.4 is the newest and use that one without them. Personally I will probably use 17 for a while longer on my main router until the 18 branch is more stable. 18.06.1 is scheduled in August already.