Wifi dropping out every 30 seconds

[newbienik]

R3 router, 3 months old, latest firmware. Channels for 2.4 and 5 are set to auto, DHCP is enabled.
Wifi was fine for about 2 months, then last week dropped out, reconnected, dropped out, etc, etc for about 5 minutes, then settled. All is well again. This has happened twice since, both times during "heavy" (30Gb download from one device) network traffic. Today, tried to set a reserved IP (at 133, no collisions) and network dropped immediately. Now, I cannot connect to wireless on R3 router long enough to open the control panel reliably. The times I can connect, i turned off DHCP and used fixed IP (no change), changed the 5ghz channel manually (no change) and am now down to factory restting the device. 
C'mon team. This router has two main features, the first one to be a router and it seems to be failing quite badly at that.
Without having to reconnect many, many wireless devices, is there a way to fix this or at least a guarantee that after resetting, I don't have to reconnect all my wireless devices every couple of months?

[newbienik]

I have now split the wifi bands and it seems that the 5ghz band is the one constantly dropping, even if I'm in the same room as the router.

[Krush]

C'est souvent lié au changement du SSID et/ou au périphérique avec une IP privée et aléatoire ! "supprimer le SSID"

Le mieux est de rendre ton périphérique ouvert/accessible au réseau local... "WIFI R3"

Paramètre réseau du périphérique_Adresse WIFI privée "non"_limité le suivi de l'adresse IP "désactivé" 

 

---- Si tu as créé un réseau Mesh après t'être connecté au WIFI principal, il te faut oublier le SSID sur tes périphériques et les reconnecter au SSID---