Morena,

As part of the house reno we have taken the opportunity to get a LAN installed (only in the ground floor of the two storey house). We have a very odd drop in network speed that is intermittent and thus far I can't identify a pattern. I appreciate there are a million potential issues and no-one will be able to tell from afar, but does anyone have any (really simple) resources about where to start troubleshooting, please?

Setup is gigabit fibre to ONT > HG659 Vodafone Modem > Orbi RBR50 mesh with two satellites in daisy chain topology, and then a wired connection from the Orbi main to an unmanaged gigabit switch in a cupboard under the stairs, and hence to about 30 ethernet sockets. Modem is set as bridge and mesh router assigns IP addresses (this is what the installers got me to do - I was all up for just ONT to Orbi and setting that to do VLAN tagging but they reckon I should use Vodafone's modem - "it's better that way" apparently, in an unspecified manner!). 

There's no double NATing going on. Running Speedtest on wifi I'm getting >900/500 with pings of 4-10 most places; same is true on the Orbi itself when I run the modem's speed check software. Running it on the LAN devices most are the same speed, but an AppleTV and a PC both return pings of about 300, and 2/1Mbs and are unusably slow connections. I have fixed a number of the IPs as static routes (for a Sonos Boost, a Hue bridge, the Roon box, the NAS etc) and all the IPs on the network are unique. Because the instructions to wire in a minimum of 2 Cat 6s to each socket didn't get passed on to the builders there are a couple of single LAN sockets that have had a small "gigacard" card that acts as a 4 port switch installed behind them, and a new faceplate with 4 sockets on popped on the wall. The AppleTV is connected to one of these, but the PC isn't, so I don't think they are the sole reason.

Does this sound like a wiring issue? All the cables are 5e or 6, and the slowness of some of the connections is so slow I assume it isn't a bottleneck from a device. 

Do I just have to disconnect everything wired and then rebuild it one it a time?

All helpful ideas gratefully received. As you can probably tell network engineering is a mystery to me so please be gentle :-) and the answer "get the sparks to fix it" is probably valid...

Many thanks in advance

b