Hello ,

Please make sure that the following domains are added to your firewall/antivirus exceptions

www2.deepl.com

api.deepl.com

Next, please ensure the API key is added correctly

https://gateway.sdl.com/apex/communityknowledge?articleName=000013232

Please note recent changes made in the DeepL plugin are only supported in the Trados Studio 2019/2021 versions.

Thank you very much Steven! It worked and now the DeepL API is running perfectly in my Studio. 

Here is what I did to troubleshoot DeepL. As I was using W10 in Spanish, I don't know if the translations of the options and buttons are the correct ones.

In Windows 10

Select Settings > Update & Security > Windows Security > Virus & Threat Protection > Firewall & Network Protection > Allow an application through firewall.
Click the Change settings button
Click the Allow another application button
Add the path to your DeepL.exe.
Click OK
Exit

In AVG antivirus

Select Menu > Options > Exceptions
Click the Add an exception button
In the field that appears type api.deepl.com
Click the Add an exception button
In the field that appears type www2.deepl.com
Click the Add an exception button
Exit

Thank you very much Steven! It worked and now the DeepL API is running perfectly in my Studio. 

Here is what I did to troubleshoot DeepL. As I was using W10 in Spanish, I don't know if the translations of the options and buttons are the correct ones.

In Windows 10

Select Settings > Update & Security > Windows Security > Virus & Threat Protection > Firewall & Network Protection > Allow an application through firewall.
Click the Change settings button
Click the Allow another application button
Add the path to your DeepL.exe.
Click OK
Exit

In AVG antivirus

Select Menu > Options > Exceptions
Click the Add an exception button
In the field that appears type api.deepl.com
Click the Add an exception button
In the field that appears type www2.deepl.com
Click the Add an exception button
Exit

Thanks , I'm sure that will be helpful for others too!