Looking at konz-lu.tk's 522 activity over the last 7 days I am seeing that this only started occurring around 2017-04-16T18:00:00:000Z (32 incidents so far)
Here are a pair of requests directly to your backend where you can see that there is clearly an issue
MacBook-Pro:~ mgalanter$ curl -svo /dev/null
https://konz-lu.tk/ --resolve konz-lu.tk:443:46.4.84.209
* Added konz-lu.tk:443:46.4.84.209 to DNS cache
* Hostname konz-lu.tk was found in DNS cache
* Trying 46.4.84.209...
* TCP_NODELAY set
* Connection failed
* connect to 46.4.84.209 port 443 failed: Operation timed out
* Failed to connect to konz-lu.tk port 443: Operation timed out
* Closing connection 0
MacBook-Pro:~ mgalanter$ curl -svo /dev/null
https://konz-lu.tk/ --resolve konz-lu.tk:443:46.4.84.209 -k
* Added konz-lu.tk:443:46.4.84.209 to DNS cache
* Hostname konz-lu.tk was found in DNS cache
* Trying 46.4.84.209...
* TCP_NODELAY set
* Connection failed
* connect to 46.4.84.209 port 443 failed: Connection refused
* Failed to connect to konz-lu.tk port 443: Connection refused
* Closing connection 0
I am seeing these errors reflected in our proxy server logs
"server": "71m126",
"flserver": "71m126",
"cacheserver": "71c126",
"severity": "error",
"pid": "3817",
"connectionId": "376449090",
"message": "upstream timed out (110: Connection timed out) while connecting to upstream",
"client": "77.47.78.205",
"request": "GET / HTTP/1.1",
"server": "71m126",
"flserver": "71m126",
"cacheserver": "71c126",
"severity": "error",
"pid": "3817",
"connectionId": "376449090",
"message": "connect() failed (110: Connection timed out) while connecting to upstream",
"client": "77.47.78.205",
"request": "GET / HTTP/1.1",
Given the recency of these errors, even though you mention that nothing has changed, it does look like something did change. I would recommend double-checking with any local technical resources you have such as your hosting provider support to see what the issue might be.
Hope that helps,
Maksim