I am sorry to hear that. It almost sounds like you suffered equipment damage due to a lightning strike (or power surge) to have that many problems simultaneously. Try swapping in a new power bar - I have seen them malfunction after taking power surges.
On the other hand ROKU’s don’t last forever. Verify that you do not have any large inductive loads on the same electrical circuit as those entertainment devices (ie. fridge, microwave oven, airconditioner, power tools). Lights dimming when a large inductive load starts up is a big give away.
Try testing the entertainment devices one by one to try to isolate a bad or malfunctioning unit. Also try different LAN ports on the Balance and verify you get an orange and green light on the LAN port when plugged in and powered up. Verify none of the LAN ports on the Balance are damaged by plugging known good devices into them.
If you have an old router laying around, use it to test these entertainment devices to establish where the problem lies. Do this one device at a time to establish whether it works or not and if it does then connect another one for test.
If one of the devices is outputting garbage onto the LAN it will crash/slow down the local area network and negatively impact other devices connectivity. Isolate the devices to establish whether they work or not.
The ROKU’s (and other devices) may be warranty claims / RMA at this point if they don’t work on 2 different routers or time to get new ones/upgrade. Call them because they might offer you a deal if you are subscribed to a lot services / valuable customer etc…
I have also heard of ISP’s having NAT (and/or traffic shaping) that interferes with streaming devices and services. You may want to contact them to see if they changed anything on their end or try doing some internet searches with their name and the malfunctioning devices in the search terms: “ROKU/Bluesound streaming problems with ISP”. If nothing is on a VLAN then your LAN computers should be able to see it (turn VLAN off on the ports under network settings etc.).
Anyhow I feel your pain. I just bought a new modem and its crashing my SURF every 4-8 hours no matter how I configure it. I googled it and found lots of people having problems with it that they could not resolve. No wonder it was so cheap! Plugged the old one back in and smooth sailing. Good times.