I have ATT fiber, 1 gig, with a BGW320-500 router and just got a new TP-Link XE70 with three Decos. I followed the guide by a user named Fergie 20 n a Ubiquiti forum on how to get my BGW320-500 in IP Passthrough mode so I could hook up my TP-Link Deco XE70 Pro mesh router. The XE70 has three ports, one of them is 2.5 Gbps and the other two are 1 Gbps. The BGW320-500 has 4 ports, a 5 gig port and 3 1 gig ports. I have the XE70's 2.5Gbps port plugged into the 5Gbps port of the BGW320-500, because I typically get 1.25 or higher Gbps through the BGW-320-500 when I test using a direct Ethernet link.

I also have a Synology NAS (a DS923+) with a 10GbE RJ-45 (E10G22-T1-Mini) in it. So, in the past I had the Synology plugged into the 5 gig port on the BGW and I would consistently get 1.25 gigs up and down when I ran a speedtest app on it (in a Docker container).

So, my question is... with the BGW in IP Passthrough mode, do I need to disconnect the Synology NAS from it as well, or can I leave it plugged into the 5 gig port on the BGW and plug the TP-Link into one of the 1 gig ports? Our computers are a few years old and don't support Wi-Fi 6, and frankly 1 gig is plenty for all the devices we have that connect via Wi-Fi. So, I'd rather have the Synology still getting the over 1 gig speeds rather than plug it into one of the TP-Link's 1 gig ports and lose that extra speed on the Synology. I have some friends and family that use my Plex server (on the Synology) pretty frequently, so I want it to have the fastest upload speed possible to handle it when three or four of them get on watching movies and shows.

Any ideas on how I this can be done, so the Synology still gets the over 1 gig speeds? If I plug the TP-Link into one of the 1 gig ports on the BGW, it won't do any good to plug the Synology into the TP-Link's 2.5 gig port, because it's only getting 1 gig from the BGW. If I plug the TP-Link's 2.5 gig port into the BGW's 5 gig port, then the only port left for the Synology is to plug it into one of the 1 gig ports of the TP-Link.

Any help would be much appreciated.