problem to online to PLC

Dear all coworkers and members I wish you the best
I have a problem with plc s7 400
model 414 2dp
as you see there are 2 stations one of them operation station and second one is engineering station both are same
both computer equipted with wincc monitoring program there are several selonoid valve witch get command from plc
we have a general problem that we cant send command from HMI I checked profibus connector and cp 5611 card all looked good
Ive checked the panel of plc and observed BF witch means bus fault and ext fault on CP 443-5 witch it means external fault on one of plc rack but second rack was ok
and all Digital output cards from ET200 is off
my main problem is that I cant connect to plc by profibus
I disconnected all connectors and installed pc adaptor cable to cpu and went to PLC=>upload station to pg but the error doesnt allow me to connect to plc
the error was : the connection to module couldnt now be configured
I want to troubleshoot this problem and go to online mode and see diagnose buffer and force some outputs to see problems
first I have to go online and see diagnose buffer how can I do that ?
second I should solve the BF and ext Fault
what do you recommend to solve those problems ?

I'll upload HW configuration and network diagram for more helps

Thanks for reading and your helps

I dropped all profibus connector from plc and set pg to plc but I couldnt connect to plc in online mode there isnt any accessible node into plc when I connect mpi cable to plc
I set mpi cable to an other plc and worked but I cant connect to this plc
how can I connect to plc
thanks for your help

If one computer will connect, and one won't - what is different between them?
Post of a screen shot of the PG settings dialog box for both.

Thanks a lot I got problem and solved in HW config port mpi used as a profibus I changed bit rate speed to 12 mg and connected with mpi and droped SFB0 to plc and downloaded program to plc and problem solved
Thanks for your support and your help