@kugiigi You are right. Thanks.

Whenever I rotate my Nexus 7 in landscape mode, I get a split screen instead of a full screen when using the web browser. Could anyone tell me how to get rid of this split?

@AlainW94 Yes I do have a /data/calibration/mac_addr file. It contains the same MAC address as the one displayed on Settings -> About.

Regarding the syslog file, here is the output for a search of @@@@:

cat /var/log/syslog | grep @@@@
Mar  7 14:44:30 ubuntu-phablet kernel: [    1.213373]  [7:  kworker/u16:0:    6] [c7] @@@@ SN rsa with sha1 verify failed!!!!
Mar  7 14:44:30 ubuntu-phablet kernel: [    1.213640]  [7:  kworker/u16:0:    6] [c7] @@@@ MAC verify failed!!!!
Mar  7 14:44:30 ubuntu-phablet kernel: [    1.213899]  [7:  kworker/u16:0:    6] [c7] @@@@ MAC verify failed!!!!

@AlainW94 Here are some errors found in /var/log/syslog:

cat /var/log/syslog | grep -i error

Mar  7 14:44:30 ubuntu-phablet kernel: [    0.591701]  [6:      swapper/0:    1] [c6] exynos-fimc-is-sensor: probe of 14110000.fimc_is_sensor failed with error -22

Mar  7 14:44:30 ubuntu-phablet kernel: [    1.532791]  [5:  kworker/u16:0:    6] [c5] [SensorHub]:MSG:AKM:408,error: 0x02030000
Mar  7 14:44:30 ubuntu-phablet kernel: [    2.003203]  [5:      swapper/0:    1] [c5] espresso_wifi_get_mac_addr:create file /data/calibration/mac_addr error(-2)
Mar  7 14:44:30 ubuntu-phablet kernel: [    2.003949]  [5:wl_event_handle: 1637] [c5] CFG80211-ERROR) wl_event_handler : tsk Enter, tsk = 0xffffffc0f35819e0

Mar  7 14:44:24 ubuntu-phablet kernel: [    9.196647]  [1: wpa_supplicant: 2415] [c1] CFGP2P-ERROR) wl_cfgp2p_add_p2p_disc_if : P2P interface registered

Mar  7 14:44:53 ubuntu-phablet kernel: [   38.413935]  [2: wpa_supplicant: 2415] [c2] CFG80211-ERROR) wl_cfg80211_sched_scan_start : Invalid sched scan req!! n_ssids:0 

and in dmesg:

dmesg | grep -i error

[  482.469508] [c3] CFG80211-ERROR) wl_cfg80211_sched_scan_start : Invalid sched scan req!! n_ssids:0 

@AlainW94 I tried again and I got the following output for syslog:

cat /var/log/syslog | grep wl0
Mar  7 14:44:23 ubuntu-phablet kernel: [    8.877130]  [6: NetworkManager: 3204] [c6] Firmware version = wl0: Nov 24 2015 11:23:00 version 7.45.71.r5 (r587357) FWID 01-ec3fd0c

@AlainW94 "cat /var/log/syslog | grep wl0" gives no output at all.

@AlainW94 from the beginning.

@AlainW94 I haven't tried to re-install Android and I am a bit reluctant to do so unless I have some evidence that this is the way to solve the password issue. I haven't tried the WiFi on Android. I replaced the factory OS with UT as soon as I got the phone. I have no reason to think that there was any WiFi problem with the factory settings. I don't know what WiFi "log files" are nor where to find them. I also don't know what WiFi band my phone is using.

The problem is that I am still in the dark as to whether the EFS partition is the issue or not.

When you wipe or format with TWRP, there are some options to choose what to wipe and what to keep. Could it be that those of us who wiped everything loose the WiFi password while those who didn't have no such loss?

I also don't know if re-installing Android would restore the EFS partition or not.

Yes @matteo I would prefer ATU to be on the Open Store. I haven't installed it. I would prefer to install lshw and hwinfo directly with apt-get install or dpkg -i. But there are some dependencies. I know we are not supposed to use these Ubuntu Desktop tools on Ubuntu Touch. However I have managed to install htop with apt-get without much trouble. There is now an app in the Open Store for htop but it may just install htop with one of these Ubuntu Desktop tools, I don't know.