Samsung Galaxy S8 Update Issue with Project Fi

I did not find online anyone mentioning about this. But after I update my S8 to Android Oreo (8.0, the latest system version), my Project Fi lost its data connections.

I found this issue after I left home taking an Uber. I was standing outside and there was no WiFi. My S8 behaved as usual until I notice there was no LTE sign in the status bar. I opened the Uber app and it said "No Internet Connections." I tried other apps and finally found my LTE was gone.

Okay, so long story short, if you encounter the same problem as I did, here is the solution. I do not know why it happens, but the update triggers a change in the network access point settings. For S8, if you navigate to

Settings > Connections > Mobile Networks > Access Point Names

You will see Project Fi -Tm is selected (there might be two of them). Click on the one that is already chosen and we'll edit the APN protocol. The update somehow changes the APN protocol to IPv6 only. Now change that to IPv4/IPv6.

Everything now gets back to normal. ūüėÄ

Convert png to eps with minimal size

Every time I try to convert from png to eps, through commands like convert or via online converters like here, the eps file is always super large. For example, a 50KB png after conversion becomes 3MB eps.

Then I figured a way to reduce the file size. It is still through convert command, but with an additional prefix inside the command. Continue reading Convert png to eps with minimal size

Unlock Samsung Gear S2/S3 (AT&T)

Not sure if T-mobile follows the same procedure but I find the original solution here for S3 Frontier (AT&T). It apparently works for S2 also. I have no idea why AT&T does not release this and claims they cannot unlock wearables (in 2016).

Here is a log of the procedure, verified by both XDA folks and me.

First, you need to get the unlock code (from here at AT&T). If you are not the account holder, ask them to follow the procedure for you. To get the unlock code, you need to find out your smartwatch's IMEI number at Settings > Gear Info > About Device. For me, the request takes about 2 business days. Some people did not get it in couple days and pinged at the customer service and went it through.

Anyway, suppose you have the 8-digit unlock code now. You get it from the email asking you to follow the procedure by first "power off the device and remove the SIM card". Yea, you can never do that for Gear S2/S3 because they use eSIM.

Thanks to slapshot2286, we can unlock the device by doing the following.

  1. Go to Settings > Gear Info > About Device and scroll down to Software Version
  2. Tap Software Version 5 times and a keyboard will show up
    • as suggested by others, under the newer version, you should tap¬†Serial Number¬†5 times¬†instead
  3. Type #7465625*638*# and another dialog shows up, which says "Personalisation" followed by "Enter NCK"
  4. Enter the unlock code you get from AT&T and tap OK

You will then see SUCCESS indicating you have unlocked your Gear S2/S3. Period.

Quickly Scan Local Network

Recently I need to quickly scan the local network and find my other device's IP address. I do not have access to the access point, and my device does not report its IP so I cannot directly get what I want. But using another device (laptop specifically), I can quickly find out the IP address of that device.

Just simply do:

for ip in $(seq 1 254); do echo $ip; nmap -sP --max-retries=1 --host-timeout=10ms 10.0.0.$ip | grep "Host is up"; done

Since we are under the same network (assuming my IP is 10.0.0.xx), we will have very low latency (so we can set low timeout). And then this prints:

1
Host is up (xxxs latency).
2
3
...
61
Host is up (xxxs latency).
...
206
Host is up (xxxs latency).
...

That means:

  • 10.0.0.1 is my gateway (access point)
  • 10.0.0.61 is me
  • And of course the one left is 10.0.0.206, which is my device's IP

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