I am a user of the tplink TL MR-6400 v3 decoder, which is no longer under warranty. I recently experienced network issues when I'm in a weak signal location. I noticed that by placing the decoder outside, the signal improves considerably.

I would like to know if it is possible to add an external antenna to my MR-6400 v3 decoder in order to improve the signal quality. If so, could you recommend a suitable antenna and provide me with instructions on how to install it correctly?
I saw on the internet that you could connect an external antenna to the decoder on the youtube site
https://www.youtube.com/watch?v=gWqWh86B200&t=8s

 I would greatly appreciate your assistance in resolving this issue.