If you have the correct URL, there must be some blockage on the way. To be able to troubleshoot this, I need your public IP to see if the traffic is reaching our server.
It's hard to tell, can you share what changes he made so we can implement it on the development server and measure?
I don't have a static ip so it keeps changing, right now it's ip 27.34.17.230. if possible please disable the IP restrictions until the issue is fixed.
Regarding the changes, you can copy the WPML multilingual CMS plugin folder itself from the live site to development site to measure the performance.