Plotting disproportionate sets of data

I solved an optimisation problem for three cases. I intend to plot the results as a groupplot (essentially a 3 by 1 groupplot). Since I present six sets of data in each plot, I get a graph that looks like this:

Due to the disproportionality of the datasets, we observe a near parallel line for 3 datasets, while the other lines show that the system design costs increase wrt routing costs. What I’d like to have is for the near parallel line to also show that the system design costs increase. However, this information gets suppressed. Could you please suggest some alternatives for this anomaly? Please find the code here

  begin{tikzpicture}[every mark/.append style={mark size=.7pt}]
    begin{axis}[
                scale=0.81,
                legend style={
                at = {(.48,-.8)},anchor=south},%at={(0.5,-0.34)},anchor=north},
                %legend columns = -1,
                xmin=0,xmax=50,
                ymin=0,ymax=400000,
                ymode = log,
                xlabel={routing costs},
                ylabel={system design costs},
                legend style={font=small}]

addplot
    coordinates {
        (0, 310006.712271894)
        (10, 312781.712271894)
        (20, 315556.712271894)
        (30, 318331.712271894)
        (40, 321106.712271894)
        (50, 323881.712271894)
    };addlegendentry{Centralised RAN}
    
addplot+
    coordinates {
        (0, 237.689033351856)
        (10, 535.932112624024)
        (20, 834.175191896192)
        (30, 1132.41827116836)
        (40, 1430.66135044053)
        (50, 1728.90442971269)
    };addlegendentry{Distributed RAN}
    
addplot+
    coordinates {
        (0, 47.5517657268742)
        (10, 404.104349185922)
        (20, 709.528125267976)
        (30, 1014.06344997298)
        (40, 1317.76112473382)
        (50, 1620.73092429476)     }
    ;addlegendentry{Fluid RAN}
      addplot+          coordinates {
        (0, 310007.104063121)
        (10, 312782.104063121)
        (20, 315557.104063121)
        (30, 318332.104063121)
        (40, 321107.104063121)
        (50, 323882.104063121)
    };addlegendentry{Centralised RAN - HIGH}
    
addplot+
    coordinates {
        (0, 93699.4500521545)
        (10, 94466.4160045098)
        (20, 95233.3819568651)
        (30, 96000.3479092204)
        (40, 96767.3138615757)
        (50, 97534.279813931)
    };addlegendentry{Distributed RAN - HIGH}
    
addplot+
    coordinates {
        (0, 90079.5312740768)
        (10, 90995.7138828325)
        (20, 91787.0309120226)
        (30, 92568.9759214698)
        (40, 93347.4344093317)
        (50, 94123.854677605)
    };addlegendentry{Fluid RAN - HIGH}
    
 end{axis}
end{tikzpicture} 

documentclass{standalone}
usepackage{pgfplots}
usetikzlibrary{calc}

begin{document}
begin{tikzpicture}[every mark/.append style={mark size=.7pt}]
    begin{axis}[name=lower,
                scale=0.81,
                height=3cm, width=6cm, scale only axis,
                xmin=0,xmax=50,
                ymin=0,ymax=50000,
                ymode = log,
                xlabel={routing costs},
                ylabel={hspace*{2.5cm}system design costs},
                ylabel shift=2cm,
                legend to name=part1,
                legend style={font=small}]
addplot+
    coordinates {
        (0, 47.5517657268742)
        (10, 404.104349185922)
        (20, 709.528125267976)
        (30, 1014.06344997298)
        (40, 1317.76112473382)
        (50, 1620.73092429476)     }
    ;addlegendentry{Fluid RAN}
addplot+
    coordinates {
        (0, 237.689033351856)
        (10, 535.932112624024)
        (20, 834.175191896192)
        (30, 1132.41827116836)
        (40, 1430.66135044053)
        (50, 1728.90442971269)
    };addlegendentry{Distributed RAN}
end{axis}
    
begin{axis}[shift=(lower.north west),
        scale=0.81,
        height=3cm, width=6cm, scale only axis,
        xticklabels={}, cycle list shift=2,
        xmin=0,xmax=50,
        ymin=50000,ymax=400000,
        legend to name=part2,
        legend style={font=small}]

addplot
    coordinates {
        (0, 310006.712271894)
        (10, 312781.712271894)
        (20, 315556.712271894)
        (30, 318331.712271894)
        (40, 321106.712271894)
        (50, 323881.712271894)
    };addlegendentry{Centralised RAN}    
    

      addplot+          coordinates {
        (0, 310007.104063121)
        (10, 312782.104063121)
        (20, 315557.104063121)
        (30, 318332.104063121)
        (40, 321107.104063121)
        (50, 323882.104063121)
    };addlegendentry{Centralised RAN - HIGH}
    
addplot+
    coordinates {
        (0, 93699.4500521545)
        (10, 94466.4160045098)
        (20, 95233.3819568651)
        (30, 96000.3479092204)
        (40, 96767.3138615757)
        (50, 97534.279813931)
    };addlegendentry{Distributed RAN - HIGH}
    
addplot+
    coordinates {
        (0, 90079.5312740768)
        (10, 90995.7138828325)
        (20, 91787.0309120226)
        (30, 92568.9759214698)
        (40, 93347.4344093317)
        (50, 94123.854677605)
    };addlegendentry{Fluid RAN - HIGH}
    
 end{axis}

node[below=1cm,align=center] at (lower.south) {pgfplotslegendfromname{part1}
  pgfplotslegendfromname{part2}};
end{tikzpicture} 
end{document}