Thanks kindly for your offer to do a test with your Ethernet to USB-C dongle. Should I want to experiment in the future, however, I'm likely to buy my own. I do appreciate the offer.
Since I prefer to stick with a wifi connection, and since it isn't certain that a new router (unless very expensive) will make a difference in my wifi speeds, I'm going to stick with my existing setup. The speeds are much improved, and more than adequate for my simple needs.
I can understand that Sonic would be hesitant to get into a 'second stage' installation involving the idiosyncrasies of individual customers' equipment. Could get complicated and require another level of expertise and training.
Many thanks to all who have contributed to this thread.
Channel 36 (5GHz, 40MHz)
Tx Rate: 270 Mbps
PHY Mode: 802.11n
I'm in North Berkeley, and in the interests of helping debug this I'd be happy to lend you a USB-C gigabit dongle. I know it's not what you want, but would at least verify the WiFi is the problem and not some other bit of your setup.