Plumbing question…..

So I have an issue - double sink (one has garbage disposal). Dishwasher connected. Both sinks have been backing up with water. I have taken the entire disposal, trap / pipes under the sink, and dishwasher hose apart and cleared. They are pristine and clear. I used an electric auger (a few times) and got at least 15 feet through. Blew compressed air and used shop vac to try to create a suction seal. Poured a bottle of draino and let it sit for a few hours. It’s definitely better but still backing up. I used a borescope and can’t navigate the elbows but I get as far as I can and there is no blockage. I suspect the blockage is occurring at one of the two elbows pictured below. Where the pvc meets the copper there is a clamp - wondering if I can simply take that off to expose the pipe and use the borescope / auger from there to locate and clear any clogs. I am not familiar with this type of clamp. I would prefer not to cut pipes if I can avoid it. Any advice is appreciated!!!

Where the pipe comes from cabinet through floor:


Following across:


To next elbow:



To the clamp that joins copper pipe:



The whole run:

 

Yes, take off that clamp and go in from there. Have a bucket handy if the clog is uphill.

And those short sweep 90s aren’t doing you any favors. Only long sweep 90s should be used going horizontally.

 

Yeah it’s a 50+ year old house ; not sure I have an option besides rerouting the entire plumbing run


I just removed the clamp and caught all the water. Ran my electric auger back and forth to the main drain line of the house which is a 3” diameter copper pipe. Got stuck there and would not move. I fear they’re going to have to cut the copper and replace with pvc. Thank the lord we have a homeowner warranty - they’re coming Monday