App freezes after Splash Screen on lower end phones

As title says, app freezes after Splash Screen on lower end phones.

Unity 2017.4.15f1
Android SDK 25.0.2
jdk1.8.0_131

The issue happens when building with Gradle, I have tried to build with Internal but I get the error:

CommandInvokationFailure: Failed to sign APK package.
C:\Users\praxi\AppData\Local\Android\Sdk\build-tools\25.0.2\apksigner.bat sign --ks "D:/Active Work/Apollo Oracle/Apollo Oracle UNITY/KEYSTORE HERE/user.keystore" --ks-pass stdin --ks-key-alias "von betelgeuse" --key-pass stdin "D:\Active Work\Apollo Oracle\Apollo Oracle UNITY\Temp/StagingArea/Package.apk"

Now a solution I have found for this problem is to try building with Internal that apparently resolves the issue, but then I have this new bug above me.

Has anyone found a stable version of Unity + Android SDK + JDK I can work with? The number of bugs I keep running into is insane.

 

Thanks for the reply, can I say crappier internals? The issue doesn't seem to be age, some of the phones are editions from this year. At first I though it must be the loading time but I've noticed there's an issue tied to Adreno GPU and a chunk of phones reporting this are Adreno.

Either way, I can't test whether building Internal instead of Gradle resolves the issue as some have reported.

The issue doesn't seem to be RAM either because the app runs on a tablet with 2GB RAM and I'm getting reports of the problem with 3GB RAM.

Edit: Some models with this problem
Moto g5 plus
LGE LG Leon
LG Stylo 3 Plus

 

Submitted, could you tell me if there any particular recommended version of Android and Java SDK I should use?

I've run in to problems with Java 9 and 10, Android SDK is always a wild stab in the dark.

 

Tried a couple of things in the meanwhile, updated to Unity 2018.2.17f1, updated to newest Android version, added Loading Page scene to see whether it was something in the Main Scene.

The updates have allowed me to build using Build System: Internal but this has not resolved the issue.