Did a new Firefox installation on my Windows 11 / Ubuntu 20.04 tablets, laptops and PCs and it works fine with Cocoontech.
New Windows Edge is a custom Windows Chrome interface. Personally have never liked Chrome. (that is my opinion).
The older Firefox (updated) installations on my Linux Laptops do not work unless I go to safe mode in Firefox. (been like this for years for me personally).
Today I let PFSense do the DNS stuff via DNS Resolver.
TV's get OTA via HD Homerun / direct connects and still using grandfathered DTV here (slammed by AT&T when they purchased DTV). Good news is they have spin off DTV as they lost much monies purchasing it.
Streaming a bunch these days using my KODI boxes. (prefer to use my Linux KODI boxes for Netflix / AOD accounts).
Just a quickie Wiki reference here relating to using any ISP DNS servers.
DNS Hijacking
My solution some 15 years ago with installation of Verizon FIOS was to utilize the Verizon FIOS box just for the TVs and create a new LAN network with an aux firewall. At the time II bridged one Ethernet interface to a DD-WRT combo wireless Firewall. This worked fine for me until Frontier took over the Verizon ISP account.
I have mentioned this before here on the Cocoontech forum.
Frontier slammed the Verizon account and I lost internet access for two weeks. They are on my S-List and hopefully will never have to deal with them again anytime in the future.
I did have to file an state attorney's complaint against Frontier at the time.
That said when it was fixed I cancelled the Frontier Fiber account and went to XFinity at the time.
So the suggested fix is to a la carte your network a bit ....
Frontier ISP box (shut off the wireless) ===>
1 - TV's requiring the use of the Frontier network (with their DNS servers) - direct Ethernet connections.
2 - Combo firewall / WAP (or separates) bridged to one Ethernet port on the Frontier box providing you with a separate Internet to ISP connected network.