[SOLVED] No wireless internet after installing Xubuntu 16.04

System:
Acer AOA110, Atom N270, 1.5GB RAM
Qualcomm Atheros AR242x / AR542x Wireless Network Adapter driver - ath5k
Xubuntu 16.04 Xenial

Environment: There are two wireless routers available: the upstream router is a Netgear N3400 (192.168.1.1) using proprietary software, the downstream router is Rosewill 300M(10.0.0.1) using open source dd-wrt. There are several other computers, printers, xboxes, phones, tablets, and one server coected to or accessing upstream router, 192.168.1.1. There is one other computer coected to downsteam router, 10.0.0.1.

Problem:
No wireless inteet after installing Xubuntu 16.04.

Symptoms:
S1 No wireless auto coect
S2 No indication of wireless coectivity on wireless indicator LED
S3 rfkill list shows "Hard blocked: yes"
S4 iw reg get shows 00

Corrective steps
C1 corrects S3 By holding the wireless switch to ON while booting changes to "Hard blocked: no"
C2 corrects S4 Executed iw reg set US (also changed /etc/default/crda last line to REGDOMAIN=US
Rebooted to permanently set REGDOMAIN to US
C3 corrects S1 & S2

sudo modprobe -r ath5k  
sudo modprobe ath5k nohwcrypt=1

# Next, determine if the corrective steps will persist through shutdown/boot cycle.
# Mixed results: No coection;
rfkill list shows "Hard blocked: no";
iw reg get indicates 00; /etc/default/crda still shows REGDOMAIN=US;
coection indicator in upper right margin grayed out;
iwlist wlp3s0 scan shows six cells
Repeat corrective steps C2 & C3 which are successful, and result in coection to upstream router, 192.168.1.1.

# Try to make the mod persistent across shutdown and reboots

sudo nano /etc/modprobe.d/modprobe.conf
options ath5k nohwcrypt

# During these efforts, discovered Atheros wireless adapter will not coect to downstream router, 10.0.0.1

# Discovered another problem. After rebooting,
iw reg get shows 00 again
cat /etc/default/crda still shows REGDOMAIN=US
# Why does this keep changing?

# Investigate settings of downstream router, 10.0.0.1

Router: Rosewill RNX300RT with dd-wrt v24-sp2
Reset wireless network mode from N Only to N/G Mixed
Reset Wireless security mode from WPA2 Personal Mixed to WPA2 Personal
Assured WPA algorithms set to AES
Reset time zone from UTC+1 to UTC-4
save & apply changes to dd-wrt

# Make permanent corrective step C3 (this seems more like a workaround rather than a true fix)

sudo nano /etc/rc.local
modprobe -r ath5k
modprobe ath5k nohwcrypt=1

Hooray! There is joy in Mudville tonight.

Summary: There were several problems discovered and corrected during this effort.
Hardware switch was set from OFF to ON
iw reg was set to US
Edited /etc/rc.local to add: modprobe -r ath5k && modprobe ath5k nohwcrypt=1
Investigated and changed router settings, as necessary.
Gsearch is your friend.

Tools used:
hwinfo --netcard
ifconfig
iwconfig
inxi -N
iw reg get/set
iwlist [i/f] scan
lshw -c net
modprobe
nano
rfkill list
wireless-info

My thanks to all who have traveled this same path before.