So, it has been a while, but here is the update on any and all issues I was having with my DIR-890L, Hardware Version: A1.
Did a factory reset and installed Firmware Version: 1.1.
Now only problem left was all of my smart switches kept going offline (as well as any other 2.4 band devices). Fixed this by:
1. turned off Smart Connect
2. disabled HT 20/40
3. removed all reserved addresses
It has now been 18 days without any smart switches or other 2.4 band devices going offline.
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The router is now solid as a rock.
Thanks,
Chet