I have a problem with reliable use of Alexa on my Echo



My problem is that sometimes the Echo can play music from my plex server and sometimes not. It seems to be connected to remote access which dips in and out. I have tried port forwarding as much as I am able and tried to follow the instructions but does not seem to work to provide reliable remote access. My plex server is on an iMac running latest software and my Plex server is up to date. When Alexa does work it works very well but unreliable. My router is Huawei 635 TalkTalk super router. Any help would be appreciated.