Both are up-to-date. In fact I did a firmware update an hour ago on the Nighthawk.
I’m connected to the Telia one via WAN using it as an access point. The Telia router is assigning all addresses dynamically. The firewall is on the Telia router, not the Netgear.
It flies; I get about 95Mbps on Speedtest, which is great out here in the countryside. Like I mentioned, I have zero issues with any other form of networking, just MSFS.
I would disable UPnP, but it’s not caused me any issues in the last 4 years on the Nighthawk. Without it I have had problems with certain Steam games needing various ports. If I get hacked, I’ll lock it down.