RT-AC5300 Random Latency Spikes


New Around Here
I've unfortunately been plagued by a very hard-to-troubleshoot issue with an RT-AC5300 router running AsusWRT Merlin.

My RT-AC5300 router will randomly experience network-wide severe latency/lag spikes. My wife and I run into this most often when we are both on the same Zoom call, from two computers accessing via 5GHz WiFi in different locations of the house. These lag spikes last ~10 or so seconds, but some are severe enough that we both completely drop off the call.

I've troubleshooted this by using gping during a few Zoom sessions to isolate where exactly the problem is happening. For example, I'll run three gping graphs to show output of ping across three different hosts: The router/AP, the ISP-provided modem (AT&T), and for an IP address completely outside the network.

Each time I tested this across different Zoom call sessions, I was able to identify that the router was not responding to pings during these spikes (and therefore neither were any of the other hosts during this time), so I took that as evidence that the router may be where the problem exists. Once I'd established that logic, I performed a full wipe of the router and minimal setting rebuild (security settings reconfigured, etc). However, we're still running into these horrible lag spikes.

One of the many fixes I've tried is scheduling reboots. I scheduled them for around 4am daily, but the last couple days I've noticed my network is completely down and my router is showing a red light. I couldn't even connect to the network from my phone while it showed this issue. It starts working if I hard-restart it from pressing the button at the back of the router, so I've disabled scheduled reboots today to fix that issue.

Before I wiped my router settings, I had QoS enabled to prioritize this sort of traffic (in hopes of fixing the issue), but it still happened. Now, after the wipe/rebuild, I don't have QoS enabled, and it happens regardless. Sometimes even getting my phone out to look something up or download an app update, it feels like things slow down and I break the network or something. Or, if we're watching something through our streaming box (hard-wired) and I begin a download on my laptop, we'll see the stream freeze to catch up/buffer or it decreases in quality. I really thought the beefy specs with this router wouldn't be thrown off by seemingly one device.

I'm not really sure what to check next. I'm close to giving up and looking for a new router, but I'd initially spent so much on this 5300 router for it to be a reliable, solid investment in the network infrastructure for many years to come. I installed AsusWRT Merlin firmware to hopefully fix this as well, but it still seems like the issues persist unfortunately.
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Part of the Furniture
Welcome to the forums @mustardquail.

What is your ISP speed? How big is your home in SqFt? What type of construction is used within?

The RT-AC5300 is not considered a router with beefy specs today. It was handily surpassed by the RT-AC86U several years ago, in fact.

When flashing between stock and RMerlin firmware, are you doing a full reset to factory defaults afterward? Without loading any saved config file and without plugging in any USB drives/devices into the router itself (particularly if that USB drive was used for amtm and additional scripts).

With your current hardware, (a 7-year-old model today (see link below) that is greatly surpassed by even an RT-AX68U), you may want to try the following to see if you can get it more stable, reliable, and performant.

Asus RT-AC5300U router review: Asus RT-AC5300: a monster of a Wi-Fi router - CNET

The links below may help you get the most out of your current hardware.

Fully Reset Router and Network

Why M&M

[Wireless] ASUS router Hard Factory Reset | Official Support | ASUS Global

Why 8 Alphanumeric SSID Characters

Control Channel Setup 2021

Reset Mini Guide + Control Channel Setup Details

Control Channel Setup (more)

And more links below...

Almost all L&LD Links

About L&LD

Fully Reset / Best Practice Setup / More

If fully resetting the router (and be sure to use all the reset methods (Nuclear Reset) too, to try to fully reset it, once you've flashed the firmware you want to use it with), doing an M&M config, not toggling settings on/off (they sometimes don't actually turn off...), and picking the proper control channels for your environment (by actually testing each one available, not by looking at pretty graphs/numbers on an 'app') doesn't get your desired results, a new router is in order.

Depending on your ISP speeds, the size of your home in SqFt, and the type of construction of your walls/floors, the RT-AX68U, the RT-AX86U, and the GT-AX6000 will be the specific models to consider today and for the near future.


New Around Here
Thank you! I had no idea it didn't have the best specs, I'd thought if I bought this one then it would be solid for many more years. But it seems like there have been some significant developments in new router hardware so I'll definitely take a look at the ones you sent!

I don't know my home's square footage off the top of my head, but I'll try and get that and add to the thread. If memory serves me right, I'm on AT&T's Internet 1000 plan w/ fiber optic. I also did a factory reset and rebuilt settings from scratch fairly recently, but still seem to have these latency spikes.

I'll definitely take a look through the links you sent, thank you for sharing them! It's so helpful to have all of these in one place while I troubleshoot this. I'll add more to the thread here if I run into issues, or if I fix it too -- or, worst case scenario, if I have to switch routers I'll check out the ones you sent.

Thanks again, and apologies for my delay in response!


Part of the Furniture
This router is still useable today, but with Gigabit ISP you have to disable all TrendMicro bloatware and make sure NAT acceleration is always enabled. Only then you have a chance to continue using it without urgent need to upgrade. Anything enabled Adaptive QoS, AiProtection, Parental Controls Web & Apps Filters, Traffic Analyzer, Web History, App Analisys (all TrendMicro Engine) will slow it down. It was a good router 7 years ago.


New Around Here
Oh wow, yeah I definitely still have all of those enabled -- I'll give it a shot after disabling them. I don't remember if NAT acceleration is enabled either, so I'll check around for where I can enable that too. Thank you!


Part of the Furniture
In Administration, Privacy withdraw all agreements, reboot the router and try again.


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