Rbk53 slowing down

[Stethorn]

I have a dual set of Rbk53 and when working are great and I get a full 500mb downloading using virgin media in the UK. The issue I am having is that suddenly the speed drops to around 30mb (checked they are still on 5ghz), you can do a speed test on the router and get a decent speed although that seems to struggle when a little with the download when you get the issue but eventually gives a decent speed close to the 500mb.
When I get the issue the only way to fix the issue is to reboot it or make a WiFi related change on the router. Tonight I have had chance to look into the issue more, I had the xbox cabled to the router so I did a speed test from that when I had the issue and got full speed. I didn't want to reboot or make any changes as I wanted to see what happens when I leave it. A short time ago I did a speed test from my phone and got full 500mb speed again so I thought great it's fixed its self, I then did a speed test from the ipad and only got 30mb.the differnce for the 2 devices, the phone was connected to the satellite and the ipad to the main router.
I have now done a speed test from the laptop that was WiFi connected to the main router and that only for 30mb speed.
So it seems to be anything trying to connect to 5ghz on the main router drops right down to 30mb, if it goes via the satellite over the back haul then the speed is 350 at the moment.
Can anyone suggest anything I can try, I don't won't to have to reboot the router every 10 days.i have already done a hard reset.

[Stethorn]

Just to add I my phone has now moved back to the main router and the speed has dropped down to 30mb for that as well now, so it's clearly just an issue with the main router. Anyyhing connected to the satellite is OK.

[Stethorn]

Just noticed it's the rbk50 and bit the Rbk53 that I have.

[michaelkenward]

That is the "kit" with Orbi Router (RBR50) and Orbi Satellite (RBS50).

What is this "main router". If it is a true router, then you might like to try putting the RBR50 into wireless access point mode.

Having two routers on a network can cause headaches. For example, you can end up with local address problems. Among other things, the other router can misdirect addresses that the Netgear router usually handles, such as routerlogin.net or the usual IP address for a router, 192.168.1.1.

This explains some of the other drawbacks.

What is Double NAT? | Answer | NETGEAR Support

It might also help if you told people what the modem is in front of this router. The model number could be useful. Is it, by any chance, also a router, with a set of LAN ports on the back?

[Stethorn]

It's a virgin media superhub 3 in modem mode. I very much doubt the modem is the issue as I can go to the satellite and full speed resumes, plus a simple wireless change such as guest wifi on and off brings the speed back to full.

[FURRYe38]

What Firmware is currently loaded?

What is the size of your home? Sq Ft?
What is the distance between the router and satellite(s)? 30 feet is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected.

What channels are you using? Auto? Try setting manual channel 1, 6 or 11 on 2.4Ghz and any unused channel on 5Ghz.
Any Wifi Neighbors near by? If so, how many?

Try enabling Beamforming and MIMO(MIMO may or maynot be needed) and WMM. Under Advanced Tab/Advanced Settings/Wireless Settings

Try disabling the following and see:
Armor, Circle, Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Save settings and reboot the router and satellite(s).