@stephenw10
No, I saw that FS.Com SFP-10GLR-31 was also recommended on the other thread but I ordered first SFP1G-LX-31.
I think I will abandon now trying to find a compatible 1000Base-LX SFP for Netgate 7100.
I plugged my 1000Base-LX SFP on my Arista for the Internet access and then 10Gb SFP on Arista and NetGate 7100 (switches acting like converter). And that's it.
Hmm, that's weird. I've seen SFP ports behave oddly across a power cycle, especially with connecting module before vs after boot. But the ix driver was patched to still allow it to attach.
I've invested some money in https://allegro.pl/oferta/cooler-master-chlodzaca-notepal-cmc3-do-15-czarna-13685545513 - this device cooled my 6100 MAX from 55-56C to 36-37C.
The 3100 internal switch port would always have required tagging there to pass tagged traffic to the internal NIC. It's possible the docs were updated but it wouldn't have worked without it.
Well, to be clear... it was on rebooting I got the error message. It has been explained to me that tmpfs(?) has taken over ramdisk duties. With only two gigs I'm more comfortable going back to a community appliance I built. Taking the 3100 to a cabin in the woods and letting time sort out what NextGate I might get. Thanks for all the help. Couldn't be more appreciated.
Just wanted to give a final update on my issue. I ended up buying a small e-lnk (LNK-M3011-SFP) converter instead of my large ISP box and it worked without any problems.
@Kermee Agreed, it was a very smooth process for me as well.
Migrating from the 3100 on our 250/250 + 5G Internet connections, I find the 4200 waaay over-powered with a CPU load ~3% where-as the 3100 was steadily around 35-40%. The two remote offices still on 3100s will receive 2100s to keep the costs reasonable.