Question Wifi fluctuating between 2 pretty consistent speeds

[NickRedMachine]

Hello.

I used to get a pretty consistent wifi speed of about 55mbps, with only the occassional dip to a lower number. However, since recently, it has started tanking to between 30 and 40mbps, and then stays there for a period of time.

I have 2 routers. One if the one that came with my provider (also the modem), the other is a Linksys, extending the signal upstairs. Both their Wifi is turned on (only the 2.4 signals).

The only thing that has recently changed in my situation is that someone had to fix a cable that had come loose in their 'datacenter'. The provider insists that that's not the problem, though, as they see no problem on their end or with the modem.

I have tried numerous things, such as changing the wifi channel. This did not make it 1 stable speed - it keeps doing the fluctuating.

Also, these wifi speed drops happen on all my devices, so it's not just one device's issue. Also, a wired test shows that the problem is wifi exclusive.

During a game download, I can look at the graph and physically see it going up and down in waves. It doesn't seem to be little interference drops (though that's obviously possible), but consistent drops to the second, lower speed. I am not experienced or knowledgable enough to know if it's a hardware issue, an issue on the provider's end, or something else entirely.

EDIT: I would like to add that the receiving end is not an issue. With numerous signal strengths, I get the same 2 typical speeds. (ie. directly next to the router, further away, etc)

If additional info is required, let me know what you need. I can provide images of the 2 speeds, but that won't tell you anything I haven't already explained I'm afraid.

 

[Ralston18]

Current connections being the following line diagram:

ISP - Coax(?)--->Modem/router --Ethernet cable ---->[WAN port] Linksys router with [LAN port] ---Ethernet cable ---> wired devices and wireless ~~~> wireless devices.

Edit/update/correct the line diagram as necessary.

Make and model of the ISP provided Modem/Router?

Only one router should be enabled.

For most networks the Linksys router would be the choice. That router is then responsible for providing DHCP IP addresses and network connectivity (wired and wireless).

Disable the router functions on the combination modem/router provided by your ISP.

Ensure that the modem is connected to the Linksys's WAN port.

 

[NickRedMachine]

ISP ---->Modem/router --Ethernet cable ---->[WAN port] Linksys router with [LAN port] wireless ~~~> wireless devices.

No coax, as it's a fiber connection. There is currently no ethernet cable coming out of the Linksys, just going into the 'internet' port (which I assume is the WAN port, as the other 4 say 'ethernet' and don't work).

The ISP provided modem is a Genexis modem from the dutch company Caiway, model Platinum-7840

Turning off the modem/router combination's wifi did not help, even with just the wifi signal of the Linksys active, it still fluctuates between the two approximate speeds of 35 and 55. (mostly the lower one)

 

[Ralston18]

What about DHCP IP addressing?

Is that Genexis modem truly just a modem or modem/router (aka combo).

Asking only to confirm because I understood your original post to say you had two routers.

Which router is doing that? Only one should be doing so and most likely that should be the Linksys.

Do you have administrative access to both devices?