My network completely stopped. Couldn't get anything to work. Couldn't statically set an IP and reach the router.

Rebooted router. nope.
Noticed even my caps had stopped transmitting.

Rebooted switch. Everything came back.

Looked at the log from my router...
Sfp-sfpplus1 fcs error on link

After rebooting the switch...
Sfp-sfpplus1 link down
Sfp-sfpplus1 link up (Speed 10G, full duplex)

Few seconds later... Everything got IP addresses and returned to normal.

Maby this post will help viewtopic.php?t=101018

Unit had been in operation for a few weeks at this point.

During lockup...
It still provided POE to a hAP AC2 and to a 5 port 260.

I guess you are using the CRS328-24P-4S+ switch, are you using the latest SwOS version?

During lockup...
It still provided POE to a hAP AC2 and to a 5 port 260

What does this mean ?

I guess you are using the CRS328-24P-4S+ switch, are you using the latest SwOS version?

CRS328-24P-4S+RM running switch OS, latest version.

During lockup...
It still provided POE to a hAP AC2 and to a 5 port 260

What does this mean ?

It means that it's POE was still active despite the fact that the switch seemed completely locked up.

Yes, what has the POE to do with the FCS error on your SFP ?
Different things...
If your problem is not related to old firmware or swOS or different configurations between the SFP speed negotiations then most probable is that you have a bad SFP cable...

The FCS error was what the router was reporting when the switch was locked up.

That cable had been used before with another manufacture's switch, and the switch never locked up.

The cable is a direct connect type where the modules that go into the router and switch are part of the cable.

I was hoping I was providing meaningful data that could be used to CORRECT whatever made this happen.

And remember... This is the first time I observed this problem at the office, and the system had been running for over a week. Infact... It was working one second then not. I was watching something on Amazon Prime on my computer at the time. I only noticed when the error screen popped up.

If you look for this error in the forum you will see that most suggest a bad cable...
If you are sure that the cable(with modules included) is 100% good, what can i say...

I would expect a bad cable to be a problem right away... Not several days later.

Especially not after the same cable and router attached to another switch didn't have this issue.

Yup... Found the other thread...
viewtopic.php?t=142969

I would expect a bad cable to be a problem right away... Not several days later.

With that way of thinking nothing fails because it was working yesterday so why not now as well... right ?
I feel like you do not want to accept any suggestion...
If you keep getting those FCS errors how difficult is to test another cable ?

There is also the fact that I ran the switch with routerOS for several weeks without incident.

@gotsprings - if the issue seems only related to SwOS and there are no cable/module issue, please report this on https://help.mikrotik.com/servicedesk/ or send an email to support@mikrotik.com

@gotsprings - if the issue seems only related to SwOS and there are no cable/module issue, please report this on https://help.mikrotik.com/servicedesk/ or send an email to support@mikrotik.com

EdPa

I have not been able to keep my system online for more than a few days due to power issues in my area. I updated my surge protection this morning. So if the pattern holds... I should have about 2 weeks of operation. But for the several days of uptime before swapping out the Surge Suppressor... FCS did not show up in the logs at all.

I just had an FCS error on an ethernet link between a brand new CCR1009-7G-1C-1S+ and a Netonix WS-26-DC. Replacing the used cable worked for me.