Test approach for Web Applications

In our team we have currently developing a web app with java/spring boot backend, odata and ui5 frontend. We have many fullstack tests (writen in protractor). This on the one hand, gives us alot of confidence about our deliverables, and they are excellent regression mechanism to avoid introducing new bugs, but on the other hand maintaining this tests, making sure tha the underlying infrastructure is stable enough, or identifiying bugs is a very painful and very timely process.

My question to the round:

1. Anybody had similiar experience?
2. If yes, how did you proceed here? What was the solution?
3. Would be highly appreciatted if you had any suggestions on the tools and methodic that you used to solve this problems..