Is this termination no bueno? 2.5G network drops

I have been fighting some disconnects on my PC and switch in general.

Topology is something like this...
Archer Router with 2.5G ports -> Cat 6 home wiring (builder installed cat6 genesis 6360) -> Office keystone/jack -> standard cat6 UTP cable -> 2.5G Zyxel MG-105 5 port switch (Def overheats) -> cat 6 flat cable (20f) -> PC with a Realtek 2.5gb (Asus TUF X870)

The symptoms are that sometimes my PC drops the connection and reconnects at 100/100, but the Synology NAS keeps it's 2.5G connection on the same switch. Another is that on the router I can see the entire port loses connection (Zyxel super hot at this point and it seems it is common, it is getting replaced under warranty) and all devices on that switch lose connection.

So far I have identified the most likely culprits being switch as 1 problem, and the cable going to the PC as another. I have moved everything to my gigabit Asus router in AP mode for now and only my PC has been dropping, so we can confirm either the switch, or wire to the switch (unshielded) being bad.

Zyxel sent out a replacement that I should get tomorrow. It gets hot enough to be uncomfortable in your hand even standing up and getting maximum air exposure without having a dedicated fan on it.

I ordered some Cat 6A U/FTP cables from Monoprice to replace both the Jack -> Switch and Switch -> PC which should eliminate that as being an issue. Hopefully that solves it. Current cables are thin UTP cables. I have tried setting the PC connection to 1GB manually as well, and still it will drop to 100 at times, even on the Asus router.

One last issue that It could be is the termination on the keystone/jack, how does this look? It could be better with less exposed wiring before it enters but I have never had it setup like this before to know any better.

id suspect the flat cable before that bit of extra exposure.

pendragon1 said:

View attachment 818948
id suspect the flat cable before that bit of extra exposure.

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There is the exposure + the bend without the jacket to support it. Either way I agree and I am replacing the cable soon.

you could easily fix it, it looks like its just a pinch-to-punch

pendragon1 said:

you could easily fix it, it looks like its just a pinch-to-punch

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Just lift the cap off and pinch back down when cables reseated?

Digital Viper-X- said:

Just lift the cap off and pinch back down when cables reseated?

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yup. pop it off and if it has tabs that go down into the groove its one of those. then you can just shuffle the wires in to where youre happy with it, push the cap back on and trim the extra. if not, id just leave it.

oh, disconnect at the source or be real careful trimming....

Dropping all the way to 100 suggests a bad line. Gigabit+ needs all 4 pairs. 100 needs 3. That's just a guess, but I'd start by redoing the keystone jacks and swapping patch cables. Patch cables first. They're cheap and having spares is a good thing. If that doesn't work I'd redo the wiring in the keystone jacks.

Also you want all the individual wires to be the same length going into a keystone jack. It's unshielded Cat6 so cutting off the plastic wrapper early doesn't really matter. You just want them the same length and you want to un-twist them as little as possible. When I put in a Cat6 or 6a jack I run the jacket into the jack, cut the wires even, and try to line of the ends of the wires with the outside of the jack so I don't have to cut off any wire.

zandor said:

Dropping all the way to 100 suggests a bad line. Gigabit+ needs all 4 pairs. 100 needs 3.

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100 only needs two pair. But downgrading on bad cable is definitely not in the ethernet spec, so who knows what rules are being followed. Negotiation happens at 1mbps, over the main two pairs, so it's really easy to negotiate to a connection that doesn't work.

If you're on windows, realtek's web page should have diagnostic tools which might tell you a bit about your cabling and help you figure things out, maybe.

toast0 said:

100 only needs two pair. But downgrading on bad cable is definitely not in the ethernet spec, so who knows what rules are being followed. Negotiation happens at 1mbps, over the main two pairs, so it's really easy to negotiate to a connection that doesn't work.

If you're on windows, realtek's web page should have diagnostic tools which might tell you a bit about your cabling and help you figure things out, maybe.

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No you're right, it's just 2. I looked it up. Thought it was 3. Not that I've really paid much attention to 100Mb in the last 15-20 years.

Bad connector can drop your speed to 100. Been there, done that. Picked up a spool of Cat6A, ran a line, oops ends didn't show up on time so I tried using a regular Cat5/5e/6 RJ45 plug. Ran at 100. Rock solid 100 too. It was probably possible to get it crimped properly on 6A, but not all that easy. The wires are thicker. Cramming all of them into a plug meant for thinner wires doesn't work all that well. At any rate I got the right plug, re-terminated the cable, and it was fine after that.

Just because the spec says negotiate over 2 pairs at 1mb doesn't mean your gear isn't checking the rest of the wires and automatically downgrading to deal with wiring faults.

zandor said:

Just because the spec says negotiate over 2 pairs at 1mb doesn't mean your gear isn't checking the rest of the wires and automatically downgrading to deal with wiring faults.

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Mostly means there's no published rules about how downgrading works though. According to spec, you should continue to negotiate to best mutually supported, even though it doesn't work...

Right now, we are humming along at 1gbps again... but it was at 100 for bit of the weekend. It seems to be happy with the cable now, when it drops back to 100 I will check again. The new Monoprice U/FTP cables arrived, so I will switch those out today along with the switch!