Not even a year ago, we replaced our old Netgear Ethernet Router and old Airport Express with a nice, shiny, new Apple Airport Extreme. Lot's o' promise. The main problem (apart from other minor hiccups you'll find on here) has been that we typically have had to soft reset the unit daily, because the connection would become completely unresponsive--including Ethernet and wireless connections. So, it was either the cable modem (which worked fine with our old router) or the Airport Extreme, which judging from a Google search is giving more users than just me fits. So, I've played with all sorts of settings, including turning off IPv6 in the unit and on all the computers in the house; that didn't seem to fix anything.
However, I may have just made some changes that greatly improved my download speed while also eliminating the need to reset the AEBS each day! We'll see if my "fix" holds up. But the speed improvement is a plus.
First, I changed from "Automatic" to 100 Mbps/Full Duplex in the Airport Utility and restarted the AEBS:
Then, I finally found the culprit: The automatic MTU!!
I couldn't believe it. Such a stupid, basic cause of such a big problem. This is most certainly a BUG.
To fix the MTU:
1. Apple Menu > System Preferences... then Network.
2. On the left, choose Ethernet , then Advanced... on the bottom.
3. Choose Ethernet tab:[From Apple - Support - Discussions - A fix for random, slow, intermittent ...]
. . . Configure: Change from Automatically to MANUALLY.
. . . MTU: Change from Standard to CUSTOM. Put 1452 then click OK. Then Apply at the bottom.