Hi all,
I just changed over my modem from the Sagemcom F@ST4315 modem, aka the Belong free modem over to TP-LINK VR600 modem from this deal. https://www.ozbargain.com.au/node/379738
My speed has increased from 16Mbps to 21Mbps. I contemplated for a long time whether to invest in a better modem and was doubtful whether the speed would increase as I couldn't find anything online about my situation. Now I know and I thought I would share my results. That being said, it probably won't make a difference to you if you are already on like say 80Mbps and gone up to 85Mbps, but 5mbps is like a third faster for me.
The wifi signal hasn't improved much though according to the wifi analyser app on my phone. The wifi signal from both modems are around -60dB where I am sitting now, but I now have 5Ghz band all to myself as none of my neighbours has 5Ghz access points yet.
If you are suffering from really slow FTTN speeds on the free modem from your ISP and wondered if investing in a better modem might help, here is your answer. The consensus online is that modems with the Broadcom chipset is the best, which the VR600 has, so if you are upgrading your modem, make sure you get one with a Broadcom chipset.
Both your modems have Broadcom chipsets, so it is unlikely to make that much of a difference. Of course when your sync speed is so low, any difference is great (which is what you said).
The 4315 has: BCM63381B0
The VR600 has either: BCM63168U (V1) or BCM63167U (V2)
That said, in situations like yours, I'd consider investing in getting a sparky to disconnect any possible other phone ports in the house plus redoing any joints that may exist. That is more likely to bring your sync speed up more than a different modem.