Improved speed leads to more issues
Improved speed leads to more issues
The setup doesn't include a metal SFP plug; it only has an optical fiber port.
Ah so it doesn't have an SFP socket you just misunderstood what SFP is? (SFP is not an optical port, its merely a way to connect various network adapters of which optical is one of but not the only one) That's a lot more complicated as you need an ONT either way (the router just has it built-in) and your ISP pairs your connection to the ONT. So even having all those settings you were given by the engineer wont necessarily mean you can use your own without their permission, or cloning the ONT serial number onto your own ONT.
The ISP device appears to be a fiber gateway, which is difficult to replace without explicit permission from the provider. It seems you're unlikely to achieve 2.5Gbps on a single unit while still paying for only 52% of its performance. The ISP likely expects you to use their gateway as your network switch or router, allowing multiple clients to share bandwidth via 1GbE and WiFi. Personally, I find this approach questionable if I'm already paying a premium for such high speeds. Ideally, your ISP should have upgraded the gateway so Ethernet ports can support multi-gigabit rates, or at least combine the bandwidth of several ports. Regardless, you'll still need a multi-gig switch on the local network to forward those speeds to wired clients and access points. Consider checking ServeTheHome for affordable managed or unmanaged multi-gig switches with reasonable power requirements.