Hi, MDB1967, Maybe I can help you ??
there are various things that affect the tranmssion and reception of Wifi and bluetooth signals:
Distance: how far the PC/Mac or other Wifi/Bluetooth equipped device(s) are from the transmitter, in this case the Netgear AC 1750
Interference: Both Wifi and Bluetooth are subceptible to interference, especially from metal (in the walls), microwave ovens and other devices..... with the 2.4 Ghz band being more subceptible than the 5 ghz band....also the channel you pick for your Wifi network is important, especially if others around you, eg neighbours, have picked the same band.....
If you hold down the "Option" key on your keyboard while picking your Wifi Network it will show you the transmission and reception speed, overall quality, channel chosen, and somewhat imporant stuff like that..... very good for wifi diagnostics......
There ARE various things you can do to improve your wifi reception and transmission:
1) switch over your Wifi Network to 5ghz rather than 2.4 Ghz and change the channel it's transmitting on...this is under System Preferences > Network> Wifi> Advanced.......
2) you may have to configure the Netgear AC 1750 router appropriately and possibly see if there's a firmware update for it, and apply it........ usually there's a special URL/Web address just for the router/modem itself and it's printed on a sticker somewhere on the outside, along with default passwords for logging into it..... Just use any old web browser that works, and type the URll/Web address into the search box at the top and then press Enter/Return on your keyboard.....you should see the entry window/screen for the router/modem.....type in the given default passwords and there you go !! you should be able to configure the router to transmit/create a 5Ghz network and turn off the 2.4 ghz one if you like, plus choose the channel......there are other things you may be able to do, but I'll just keep it simple for now......for the firmware update, go to the manufacturer's/maker's website, then support ???? type in the router/modem's model number or type, under Search, or look for a firmware update..... there may be one for it......then again, I don't work for Netgear or Apple, so can't say for sure with certainty....
3) consider getting a Wifi Extender or "Mesh" wifi system of some kind..... you can/could also buy a WIFI over Power line system...
I use an Airport Time capsule as my main wifi transmitter, with my router/modem plugged directly into it....and an Ethernet cable going directly to my mid 2012 Mac Pro.... I also have an Airport Extreme in my living room which is used as a Wifi Extender.....it works OK for the most part.....
4)( I think the wifi card in the 2008 might be close to the one in the 2012, but not exactly the same.... It Could be that the wifi card has failed/is failing, that is certainly possible (I've never had it happen, though)
what you could do is to swap the wifi card for one of newer/more modern design and construction.... you can also get a Wifi/Bluetooth PCI-E card for your Mac Pro that has external antennas that would go out the back of the Mac Pro.....any Mac Pro...
so, that's almost it from me.... OSX wifi makes a nice upgrade card, but it is Pricey , and there are others who may make one.... plus there are official/generic wifi/bluetooth card replacements available..... I have actually installed/swapped out both a Wifi and Bluetooth card successfully, so it is do-able, but you need lots of patience, the ability to put up with frustration.... a small screwdriver (Phillips #OO, #O, or #1) very good hand-eye coordination, a light touch, and a good set of tweezers, as those antenna connectors are tiny, fussy, fiddly and somewhat delicate, and getting then onto the posts/connectors on the card itself....can be...tricky......
I see you are on High Sierra.....well, OK !! might there be a reason you don't want to upgrade to Mojave? If you wanted to, you could possibly go to El Capitan....I'd definitely stay Away from Yosemite as it has a bad WIFI bug in it...... ie, with Yosemite WIFI doesn't work.....
hope this helps you....I'm just a Mac user here same as you
John B
