How to troubleshoot intermittent, slow speeds over the internet?

[road hazard]

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Server A is Debian 12 and is located at my house directly plugged into an ASUS AX86U router. Server B is Debian 12 and is located at my brother's directly plugged into an ASUS GT6 router. I have AT&T 1 gig symmetrical and he has Comcast 1.2 down/35 up. I recently moved my backup server to my brothers house and -sometimes- when the backup runs, we get about 45-50MB/s but MOST of the time, it's about 3MB/s. In a perfect world, we should be able to get about 90-95MB/s (maxing out my upload speed) but the internet being the internet and peering agreements sometimes being garbage, I was hoping that the 45-50MB/s would be consistent but it's not. Even before I moved the server to his place, FTP and iperf testing would (on a great day) max out around 50MB/s but most of the time, 3MB/s.... 5MB/s..... just crummy speeds. Since we're both residential customers, I know that trying to get AT&T or Comcast to solve this problem would be pointless but what testing can I do to 100% rule out anything within our control is causing these totally random speed fluctuations?

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[coxhaus]

Why don't you do a trace route? At least it will give you the path. Look for bottle necks.

 

[ColinTaylor]

How to troubleshoot intermittent, slow speeds over the internet?

Server A is Debian 12 and is located at my house directly plugged into an ASUS AX86U router. Server B is Debian 12 and is located at my brother's

www.linuxquestions.org

Even before I moved the server to his place, FTP and iperf testing would (on a great day) max out around 50MB/s but most of the time, 3MB/s.... 5MB/s..... just crummy speeds.

So are you saying you were getting the same poor speeds to the server when it was on your LAN?

What network protocol are you using for the backup process.

 

[road hazard]

Why don't you do a trace route? At least it will give you the path. Look for bottle necks.

Traceroute doesn't show anything horrible, highest hop is 30ms.

 

[road hazard]

How to troubleshoot intermittent, slow speeds over the internet?

Server A is Debian 12 and is located at my house directly plugged into an ASUS AX86U router. Server B is Debian 12 and is located at my brother's

www.linuxquestions.org

So are you saying you were getting the same poor speeds to the server when it was on your LAN?

What network protocol are you using for the backup process.

Nope, when the backup server was on my LAN, I'd max out the 1 gig switch and network cards.

I'm using rsync (ssh) to back up to the remote server.

 

[coxhaus]

Traceroute doesn't show anything horrible, highest hop is 30ms.

Then it is on your side of the network either local or remote since you own the bandwidth.

 

[road hazard]

Any iperf experts in the audience? I was using iperf and iperf3 to my backup server and here's what I was getting: (see attached file)

 

[sfx2000]

SmokePing - About SmokePing

oss.oetiker.ch

 

[tgl]

Any iperf experts in the audience? I was using iperf and iperf3 to my backup server and here's what I was getting: (see attached file)

Those results are all over the map. If you don't explain what conditions each test was run under, it's hard to make sense of them.

 

[road hazard]

SmokePing - About SmokePing

oss.oetiker.ch

Thanks, I'll work on getting that set up soon.

 

[road hazard]

Those results are all over the map. If you don't explain what conditions each test was run under, it's hard to make sense of them.

All this was done by plugging the server at my house directly into the AT&T fiber ONT (bypassing my router) and the backup server at my brother's house was plugged directly intro his Asus GT6 router. The main server and backup server have dual NICs so we tried both.....new cables....nothing helps.

When I would get these weird speeds from my brother, I'd immediately switch to some iPerf test severs and would max out my connection consistently. Switching back to my brother, speeds were hit or miss. This is looking more and more like a peering/routing issue to him that is beyond my control to fix.