Thank you but it doesn't work. Could you please check it out ?

Dear Konstantinos Gkekas,

Try next by go in sh404SEF URL Manager and search for front-page, I guess you should get SEF links that are related to Home page. Delete those URL and browse the site and test.

If you didn't create much changes in sh404SEF (like custom URL, meta information and etc) maybe you could purge all sh404SEF cache.

In this case, sorry I don't know how to help you more .

Thanks & regards!

No it doesn't work.

thank you for your support.

Dear Konstantinos Gkekas,
Please try to disable sef404 and enable language filter plugin. If it the problem is getting fixed you could check sef404 forum if it is a known issue or to make a new question if they could help you.

Thanks & regards!

sh404sef replied that since their plugin works with the default template and module position i should contact you.

this is my forum post at them :

anything-digital.com/forum/extension/sh404sef/9431-multilingual-site-home-buttons-redirects-to-english.html#p56441

Dear Konstantinos Gkekas,

Please check your account FTP, we couldn't get access.
This issue required many times to check, as soon as we finished we will let you know
We highly appreciate your patience during this process.

Thanks & regards!