Slow download but good upload speeds

[jrhead]

We have 1 GB DIA circuit and the download speeds are only running around 75-100 MB.  The upload speeds are around 800-850 MB where it should be.  

This is occurring for both wired and wireless clients.

Connecting my laptop directly to the ISP router I get 800-850 mb both directions so it is not with the ISP.

We have two MX105 running 19.1.5 but the issue was occurring with 18.211.2 so I do not think it is a firmware issue.

This issue started within the last 30-45 days.

[RaphaelL]

Hi ,

Any Group Policies or Shaping on the MX that could limit the bandwidth ?

What is the link speed ? 1000 full duplex ?

[RWelch]

Is your uplink configuration set according to your ISP bandwidth speeds?

Dashboard > Security & SD-WAN > Configure > SD-WAN & Traffic Shaping

 

[jrhead]

This is what I currently have set but have tried 1000 for both directions.

[RWelch]

If your ISP is 1Gig pipe you'd def want to set it at 1000 up/down so the MX knows it's bandwidth limits.

The only other thing I might suggest is doing a factory reset on your MX105 to allow it to pull the config from the cloud again to see if there was perhaps some hiccup.

[RWelch]

I've not yet ran MX 19.1.5 yet but MX 18.211.4 has been rock solid for me.

[jrhead]

18.211.2 was running great for months.  

[RWelch]

What is the per-client limit set under Global bandwidth limits?
Dashboard > Security & SD-WAN > Configure > SD-WAN & Traffic Shaping 

[jrhead]

Unlimited

[RWelch]

And as @RaphaelL suggested, maybe checking to see if the clients have any group policy set or tied to that particular VLAN.

[RWelch]

An option could be to locally set the MX uplink to 1Gig manually if your ISP equipment isn't newer-ish equipment...the MX has the multiGig 2.5 uplink which could be problematic.  Not 100% sure but you could test the uplink set to 1Gig and see if that helps any.

[Rob2041]

Agree here, Make sure the links from your ISP to your MX are full duplex 1gbps, also same on the LAN side. You could also try testing the speeds directly connected to a interface on the MX instead of the downstream switches to rule things out.

[nerdocrat]

I had a similar-ish issue a few months back. I know the fix doesn’t make the most sense, so please bear with me.

The short version is we discovered legacy SFPs on the network. As soon as we replaced them with the usual model, then it all went back to normal. 

The longer version is a power outage lasted longer than our backup generators could support. When it all came back online, our speeds were different - good upload speeds but poor download speeds.

My full-stack Meraki setup let me reproduce the issue on various MX and MS firmware versions. Also, I mostly skipped checking the individual links, because I had identical SM fiber SFPs all around with no CRC errors (or similar).

However, after extensive searching, my team located only one pair of outdated MM fiber SFPs on a single link connecting our MXs and a core switch. The issue vanished the moment we replaced it with identical SM SFPs.

The reason I say this doesn’t make the most sense is two-fold. First, the problem was observed while I was directly plugged into the MX - and not a switch using the MM fiber link. Second, the problem only appeared after a power outage caused a complete power cycle of the network appliances. (I see it as a problem that was lying in wait, then appear after a reboot.)