1. "Can't reach the site" is not related to the theme, as the error happens before the page is even shown (the theme code does not run at this time). This means your browser was not able to find the server / site.
In most cases this is due to Wi-fi issues or server issues. Please take a look at https://productforums.google.com/forum/#!msg/chrome/c9BghaOvRXM/QjWi-5cCBQAJ or http://troubleshooter.xyz/fix-this-site-cant-be-reached-error-gooogle-chrome/
You may need to check your computer or server.
2. Gtmetrix may not be showing the correct loading time as you have videos on your page. Videos don't load all at once, but are loading in the background while the video is playing.
From my tests you site has : 46 requests, 2.1s mb in size and finishes in 2-3s, which is fast.
We see that your site is optimized quite a lot (using gzip, script minification, etc.), so you did a great job in optimizing your site.
We have also tested your site on https://tools.pingdom.com and https://www.webpagetest.org and in all cases your site performed great (about the same as the above tests).
We don't see any issues with the performance of your site. As mentioend, the 90s results are not correct results as in those cases the test is waiting for the videos to fully render, which takes a long time.
We have written our PHP and JS using best practices (eg. WordPress Codex) and our code has been reviewed by Envato. We have taken steps to making sure our code is optmized and well written.