[Bloat] Good Wi-Fi test programs?

[Rich Brown]

A local company is rolling out fiber-to-the-home. Subscribers are switching from crummy Comtrend or ZyXEL DSL modems (whose PPPoE interface runs at 3 to 20mbps) to Calix GigaCenter equipment with symmetric ISP link speeds starting at 25mbps on up.

The complaints I've started to hear are that the new Wi-Fi signal "is weak" - not reaching as far as the DSL equipment did, and that speeds are abysmal (one report is 2.4mbps down, 0.25mbps upload). 

Before I insert myself into the "unhappy customer" loop, I would like to ask this august group for thoughts about things to check/test programs to run/phenomena to consider.

I would first do the following "easy tests":

- Check for conflicting/overlapping Wi-Fi channels. I am fond of the free app, WiFi Analyzer from farproc (http://a.farproc.com/wifi-analyzer) for this test, but there are several similar Android apps. 
- Compare the signal strength for the DSL modem and the Calix modem, as shown by WiFi Analyzer 
- Be sure that all computer(s) are using the Calix modem.
- Use a variety of speed tests: DSLReports, Fast.com, other favorites?
- Compare speedtest results when the test computer is close to, or far from the router.
- (If possible) compare the performance for both Wi-Fi and Ethernet
- Shut off the DSL modem on my way out the door to be sure it's not causing interference or confusing the situation.

Anything else you'd recommend?

Second, are there other more fine-grained/analytic tests that I could run? I'll have a Linux or macOS laptop that I could use to look at other measures: retransmits, CRC errors on the Wi-Fi link, etc. And, finally, what do I recommend based on the information gained from those tools?

Many thanks.

Rich