Before replace an old NAS, is it worth upgrading the Network?

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While I wait for a new DSx22 I have been pondering upgrading my home/office network. 

Current setup:
ISP 1 Gbps Down  / 750 Mbps Up (Fiber into the modem)
ISP provided Modem/Router (Bell Home Hub 3000)
 - DS213j
 - PS4
 - TV
 - TP-Link M9 Mesh (WiFi connection to 2nd unit)

2 computers are used wirelessly M-F
 - One uses the HH3000 and gets a good High-speed connection
 - The other connects to the 2nd M9 and has a slower connection (but generally good enough for Teams calls)

My question(s) is:
Do I buy a Switch If so, do I put it before the HH3000, or after?
Or
Do I buy a Router, and replace the HH3000? (I'd like to have more than 4 ports though)

I understand that the Synology will likely still only have 1Gbe. If I'm lucky, it'll have a 2.5 or 2x 1Gbe ports. if so that'll make for local network improvements, but Highly doubt I'll have anything more than 1Gpbe Internet for a long time. 

My goal would be: a faster internet connection for the second computer, a faster connection to the New DS#22, and a more stable connection.

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M9 should be pretty fast - 2134Mbps AC. Make sure it's appropriately configured and you actually connect t this instead of the main router. Try mobile signal strength apps.
Maybe it is time to switch to WiFi6. Maybe rt6600ax https://www.synology.com/en-us/products/RT6600ax. I know two of these in a mesh replacing your M9 would be an expensive option, but they are fast.
Alternatively, you could look at these mesh points.
Netgear Orbi https://amzn.to/3R1zcNZ
Deco X60 https://www.broadbandbuyer.com/products/...60-3-pack/
RBK853 https://amzn.to/3C7ZUjA