Blocked sinks, gurgling and toilet flush problems

[Asgeir]

Started having drainage problems yesterday. The washing machine waste pipe backed up, so did the kitchen
sink. I have an upstairs bathroom (toilet,sink,shower) and a downstairs toilet and sink. The downstairs
toilet sink backed up also. The upstairs bathroom all drains like normal, but when I flush the upstairs
toilet the downstairs toilet lets out a loud gurgling and the bowl fills with dirtier water. But when I
flush the downstairs toilet by itself, it flushes fine, no gurgling or dirty water in the bowl.

I have snaked the pipes from the washing machine side, kitchen sink side, and both toilets and toilet sink.
It helped a little in that things drain slowly now but gurgle a lot. The problem with the flushing of the
upstairs toilet affecting the downstairs toilet has stayed the same.

Any advice is appreciated, I don't really understand the toilet flushing problem at all...

 

[oz-plumber]

Sounds like you have a blockage somewhere.
Could also be a venting problem.
Do you have a vent to atmosphere or do you have AAV's.

Whatever you've got is not going away and will only get worse.

You will most likely need someone with a drain camera to see whats going on and locate the blockage or other problems.
Best solution is to water-jet the drains and clear them all out, depending on whats causing the blockage

Be prepared for a surprise on what it will cost - none of this comes cheap.

 

[snowhead]

You have a partial blockage downstream of the downstairs W.C, that means closer to the main sewer.

As OZ, it needs jetting and or camera inspection from outside back towards the property