OK, some more detail on what is happening.
DIR-868L is downstairs in the home office.
DAP-1525 is upstairs in the family room.
All of the numbers below come from me sitting next to the DAP-1525 (literally 6 feet from my chair).
When I first installed it, I could connect at ~150Mb/s. Lately it has been running at only 72Mb/s.
Both of the devices are running 2.4 and 5GHz and both have the same SSID.
When both of the devices are on the same SSID I can connect and move throughout the house and never have to change accesspoints, though I rarely move devices. Initially, under "auto" they were both defaulting to the same channel and it seemed like I was having "flaky" problems with things going on or off line all the time.
When I set the SSIDs to the same name, I get 58Mb/s, here is what it looks like:

The C0 MAC address is the one from the office downstairs.
When I change the SSID to different names, now I can see both and I get 72Mb/s from Upstairs and if I connect to WLANfruehe it is 42Mb/s:

In this one you can see the two different MAC addresses (associated to WLANfruehe and upstairs). I am running both 2.4GHz and 5GHz which is why each has 2 entries...
Not knowing exactly what is going on, I would surmise the following:
1. The DIR-868L is far more powerful, so it "over rides" the 1525 which is actually closer to me when they both have the same address, thus you see the C0 MAC address and lower connection speeds.
2. The DAP-1525 takes over, only when it is on its own SSID.
3. When they are on the same SSID, they could be "battling each other", which is why I was seeing dropouts as they were switching back and forth between access points.
I am smart enough to understand multiple access points, but my wife is not. Is there an easy way to set all this up so that there is the best performance, but minimal headaches?